Comedy: Pappy's Fun Club, Just the Tonic @ The Caves, Edinburgh

Judging by the sketch shows on offer, the unofficial Fringe sketch show rule book must state that sketch troupes must wear colour-coordinated outfits, must aim for style over substance, and must revolve around painfully contrived situations. There are brownie points on offer, it seems, if you can nod to Python, Pete and Dud or the Footlights.

In recent years, We Are Klang! showed us how to rip up the rulebook and played merry hell with the clapped out stage genre. Pappy's Fun Club hail from a similarly anarchic angle and are also a welcome addition.

As with the Klang trio, the twentysomething Pappy's have discernible personalities: Ben Clark, who looks a bit like Shaggy from Scooby-Doo and is similarly spacy, Brendan Dodds, the boyish one with a nervous smile, Tomos Perry, the flushed-cheeked buffoon who fancies himself as a leader, and Matt Crosbie, the small, bespectacled one with a touch of Woody Allen.

Loosely framing the songs and sketches are two storylines that mesh together: one is that Pappy, the group's benefactor, was ill in hospital, and the other is that the group's tax returns urgently need doing. They end up getting a warmongering Celtic warrior to help with the latter.

During the show, Crosbie dresses as Abraham Lincoln and sings about getting shot to the tune of "Consider Yourself" from Oliver!, and laments his breakfast choice of "fourscore and seven eggs". Elsewhere, the group perform a montage of horror film trailers, the kind that would be made including: "thinking that you have lost your phone when you are actually using it".

A more pointed routine lampoons the plethora of undercover journalists in positions of responsibility, in this case hospital doctors. The scene unmasks one of the doctors as playing multiple roles in the life of one of the other characters, a modern twist to the idea that "it was me all along".

Always enjoying themselves, the audience are carried with the quartet, giggling as they pretend to be Bob Dylan's backing band and indulging them through a childish section where they pun their way through a sketch playing personifications of the directions, up, down, left and right. It's an opportunity for the personalities of the group to shine through word-play and to give the show added value.

Ad-libbing abounds and there is genuine corpsing here and there, though it does not became integral to the anarchy as the choreographed corpsing does in We Are Klang!. Clearly knowing each other well on and offstage, Pappy's Fun Club are never as choreographed as some of the "boy band"-style sketch troupes that abound on the Fringe and are a triumph of personality over format.

To 26 August, not today (0131-208 2351)