I always wear really, REALLY big pants around the, just in case this situation should arise........ I don't have to choose just one!!!!
However, if I happen to be lounging around in my Speedo (it's a bit too big, so I wear suspenders to keep em up, but that's not important here) I'd probably grab my 1/48 Classic Airframe P-51H, just because everything else I have is still readily availiable. I could probably get a 1/72 Academy kit down the front of my speedo too.....not much in the way there, as I am hung like a fieldmouse!!!!