When you arrive for a show and get handed a mini water pistol, you know you’re in for an interesting evening. And it turns out that the opportunity to gleefully drench some actors is actually one of the least eccentric things about the Lampoons’ Attack of the Giant Leeches, a comedy horror for the Halloween season, which is very funny, extremely silly and above all quite, quite bonkers.

It’s the 1950s, and something bad is lurking in the Florida Everglades. When a local man claims to have seen a monster in the water, nobody believes him… but then people start disappearing, and game warden Steve Benton vows to track down the culprit. The show is a madcap homage to the 1959 “creature feature” movie of the same name, complete with low-budget props, rampant sexism and some very questionable accents.

The Lampoons describe their style as “engaging, eccentric, and visually banterous”. I’m not even sure if banterous is a real word, but it feels appropriate nonetheless. The actors are clearly having just as much fun as the audience, bickering cheerfully amongst themselves and occasionally collapsing with a fit of the giggles. The show also enjoys sending up the style it’s imitating, with scenes of clichéd melodrama, cheesy commercials for household products, out of the blue musical numbers, and – perhaps most memorable – the moment the solitary woman breaks character to launch a furious and long overdue tirade against her patronising male co-stars.

Each of the actors (Christina Baston, Adam Elliott, Josh Harvey, Oliver Malam and Sab Muthusamy) takes on a number of stereotyped roles, among them the country yokel, the henpecked husband, the seductive blonde and – of course – the hero who saves the day, albeit with a lot of help from his considerably more intelligent girlfriend, and an unnecessary amount of time gazing dramatically into the distance. It takes skill and a well-oiled team effort to produce something that seems so completely chaotic, but this cast certainly knows how to deliver – and how to get maximum laughs while they do it.

A word of caution: this is not a show you just sit and watch – and don’t think just because you avoided the front row that will get you off the hook (I realised this when, in my ‘safe’ second row seat, I suddenly found myself being handed a stick of dynamite made out of a Pringles can, by an expectant-looking man in a rubber dinghy). The cast throw everything into their performance, but they also feed off the audience’s reactions, and without that participation – and in some cases, severe discomfort – the show would probably fall a bit flat, so be prepared to get involved.

Don’t expect serious drama or highbrow acting from Attack of the Giant Leeches (although who would, with a title like that?), but what this show does offer is full-on entertainment with a side helping of complete mayhem. It might not give you nightmares, but it will definitely give you a surreal and hilarious night out… and who can say no to that?