Your second thought is to find a policeman - but they are in little evidence, having been heavily stoned a while back. Instead, relax and follow the example of your taxi driver: lean forward, and make a complicated finger gesture with your fingers and thumbs. Instantly, the lads climb off the roof, the crowd parts, and everyone smiles and cheers.
Five days before polling, Indonesia's election campaign came to an official end yesterday, marked in Jakarta by a final round of stone throwing and tyre burning on the part of demonstrators, and tear gas firing by the police. But the atmosphere in Jakarta yesterday had more in common with the build up to a tense Cup Tie between Celtic and Rangers than a general election.
On paper at least, Indonesia's election is very straightforward. There are only three parties, each one licensed and organised by the government. There is a similarly restricted choice of candidates and, when polling takes place next Thursday, the result is in absolutely no doubt: 32 years after he came to power as a young general, the Golkar party of President Suharto will win another handsome majority. But for all the restrictions facing them, Indonesians have managed to create a rich political iconography, complete with colours, symbols, songs, arcane hand gestures, and accompanying merchandise.
Yesterday's troubles focused on the greens - the adherents of the United Development Party (PPP), which draws its support from Indonesia's majority Muslim population. There were green kites in the air, green banners fluttering from the lamp posts, and green T-shirted gangs parading through the streets banging green-painted oil drums with goatskins stretched across them.
The PPP appears first on the ballot papers, so its hand symbol is the single raised thumb. Several of this week's numerous fights have occurred when thumbs have met V-signs, the symbol of the yellows - President Suharto's Golkar. For the third group, the Indonesian Democratic Party (colour: red, symbol: bull), things are even more complicated - after a split last year, the PDI now has two factions, each of which has its own sign.
Even the forces of order have their own colours - prominent on the streets of Jakarta yesterday were men in black boiler suits, carrying automatic rifles, whose pink berets identified them as Indonesian Marines.
Indonesia's leaders like to refer to the election as a "Carnival of Democracy", as if acknowledging that the result counts for much less than the performance. Recently a new colour has entered the political palette - white, the colour of abstention, propagated by those who see it as the way of registering a protest at the unfairness of the system. For all the atmospherics of the campaign,Indonesians know that having flown the kite and bought the T-shirt, nothing is going to change.