Jermaine, powerfully built for a boy of 14 and a promising athlete, did not have to explain. The 'stuff' going around this school and thousands like it is illegal drugs, such as marijuana and crack-cocaine. Both he and Heather steer clear, however, and have no qualms about proving it.
Nor are they alone. Last week, 180 children aged between 12 and 14 - about one-third of the pupils at this school in Anderson, Indiana - formed a line outside the main boys' and girls' toilets to take part in an extra-curricular activity unlike most others they had tried before: a mass screening for narcotics abuse.
The children were all first volunteers in a novel and controversial drugs-prevention programme being pioneered here which, if successful, may be taken up by schools across the country. It is unusual not just because it introduces testing to the classroom for the first time, but also by virtue of the material gain it offers to pupils who come up clean.
The lure of reward is at the heart of the experiment - and explains why so many children joined in. Anyone showing negative - all 180 of them last week - can expect to be issued with laminated identification cards stating their drug-free status. More important, as far as the children are concerned, the cards will earn them generous special discounts in local shops and fast-food restaurants. They can look forward, for instance, to cheap pizza, free rounds at a local mini-golf course and dollars 3 ( pounds 2) off compact discs.
'The point is not to punish them but to give them an incentive to stay clean,' explains David Chilcote, a social worker at the local hospital who helped launch the scheme at a recent conference in Dallas, Texas, broadcast to 800 US hospitals. 'We've tried just about everything but rewarding the kids. We've tried to scare them and punish them and none of it has worked. So now we're going to try this and it's pretty exciting.'
The mechanics of it are fairly simple. Those pupils who took part here first had to get written permission from their parents. They were ushered into the toilets one by one to fill their beakers. The hot water supply had been turned off to make sure no one attempted to smuggle in an old sample and warm it up to body temperature, courtesy of the hot tap. The whole crop was then taken back to the hospital for immediate screening. Drugs taken even up to 45 days beforehand can be easily detected.
As part of the programme - dubbed International Drug Free Youth or IDFY (pronounced 'I Defy') - card-holders will be expected to set up classroom clubs with their own activities and by-laws. Meanwhile, about one in 10 will be selected randomly over the next 12 months for follow-up screenings.
In line with Mr Chilcote's determination to eliminate all threat of punishment, children who test positive at any stage in the programme will face nothing worse than being denied the discount card. The infraction will not be entered in any school records, nor will parents be informed. It is this part of the scheme, Mr Chilcote freely admits, that causes most controversy. Not all the Anderson schools, for instance, have yet agreed to take part.
But Bruce King, the principal in this school, situated in a relatively poor and racially mixed part of the city, has no such hesitations. 'Kids need privacy, they have their own lives, you know. This is just meant to be an incentive for them to clean up their act,' he says. He was especially gratified that so many of his pupils entered the programme. 'I had kids down there who, frankly, I had doubts about,' he admits.
Nor does David Reed, one of two uniformed Anderson policemen who daily walk the corridors of the school, have any doubts. His department is looking for ways to back up the initiative, perhaps by letting off children found at under-age drinks parties who are able to produce the drug-free cards. 'That could be the perfect time for them to tell us they belong to 'I Defy'. We could maybe then issue them with a certificate of appreciation,' Mr Reed says.
The patrolman has no illusions about the drugs problem in Anderson, a medium-sized city of about 40,000 people just north of Indianapolis. Supplies, of crack in particular, flow in growing quantities down Detroit and Chicago. One of Mr Reed's colleagues recently arrested two 17-year-olds trying to sell what they said was crack to two 10-year-old boys in a public playground.
So far the response from city traders has been encouraging. About a dozen establishments have promised to sign on to the programme - including the golf course, a cinema and a shop for baseball-card collectors. They will shortly receive special IDFY stickers to advertise their readiness to give the children discounts. 'We are very keen. I feel we need to do whatever we can to educate the kids. Whatever it takes,' says Peggy Murdock, owner of a sandwich shop.
The success of IDFY will rest ultimately on reaction in the schoolyard and peer pressures. If the discount cards come to be 'cool' - Jermaine hopes to use his to expand his training shoe collection - perhaps they will work. But there must be a risk that they will be seen instead as a badge of 'goody goody' compliance with authority - in other words, not cool at all.
Heather, a sparky 13-year-old, is optimistic: 'You know, until now, it was always the bad kids, when they get into a fight or something, who got all the attention. Now maybe it will be us.'