I was thinking training montage, with Eye of the Tiger and everything.
In all seriousness, picture your dude’s face! He will have forgotten all about that bet (he might have even now) and one regular sunny day you CASUALLY walk on over to that conveniently located stage; “hold that drink for me for a second, honey”, and BAM. He won’t know what’s even happening, crying into both of your milk shakes in joy and confusion.
Plus, you’ll be super buff. There’s no downside, really.