That's not a lack of punchline, that _is_ a punchline. It's a reference to the awful jungle hit by M-Beat and General Levy called "Incredible".

piss off, short lived music genre my ass, still going strong, and previous poster is a moron, the joke is a word play on the famous m-beat song 'junglist massive'

The joke is that you don't say 'Because the jungle is massive', you pronounce it 'Because junglist massive' (in reference to the actual lyrics of the MBeat track). Like most humour, it's all in the delivery...

junglists and the junglist massive and hardcore junglists are all known mc terms for producers, fans of jungle or the crowd at a jungle rave ... it's cause the junglist massive you amateurs