Thanks for the advice so far guys, and thanks also for the word up on it being called 'regimental' instead of 'commando' or 'natural'.
My mate reckons that by wearing a kilt and wearing nothing underneath will get him plenty of 'play' at the party but I assure you guys that nothing will happen as the girls I know are not 'that way inclined' for a quick one and are always responsible with their alcohol consumption. Boring guys I know
I am lucky I suppose in that I am pretty good shape ( turning 21 ) and so have a flat stomach and a reasonable **** that helps keep the kilt up ( thank god for my dad's genes in that department as well - no flat **** ) and all in all I am happy with my physique and am able to wear a speedo with not too much self conciousness of how revealing it is. Which makes me think it will be sooner, rather than later, that I go regimental with my kilt.