That is a super hot story Sniff. Wish I could have joined you in that truck. I'd huff his nut scent so hard his jock would be clean after I was done.
I have daydreams of finding just the right workout bud to hang with and work out at the gym. After his session, he would leave his gear laying out so I could sniff them while he's in the shower.
As for buying underwear, a guy might get me to do it if we made the transaction a minute or two after him wearing them. Especially if he shot a load into them. I've hinted from time to time to my Str8, 'ex-gay for pay' buddy that the 'least' he could do is fire off a load in a shorts and leave me the shorts. So far, he finds the idea very, very unappealing.
Would work for me though.