A live piglet (or preferably several) introduced into the proceedings during the speeches is a guaranteed way of livening things up!
Saw a remotely triggered farting machine in a gadgets shop at Birmigoom airport the other day. An amplified loudspeaker with various pre-programmed noises which can be set off by remote control. Now
that has definite Dining-In night speech potential......
Another 'ice breaker' is to fablon err, 'rude pictures' underneath the Stn Cdr's place mat - or, even better, the senior guest's. Nothing will happen until just before the loyal toast when the mess staff whip the place mats away.......
But one of the simplest - and cheapest - is just to stretch cling film between the seats and the pans of the ladies loo thrones