Answering for my hubby as he wears mens thongs quite often outside work. He said its usually plain old boxers for work, nothing special or risque. He said he's worn a thong a couple of times but thats all.
I have worn the missus's underwear, as well as some male lingerie before, and do enjoy it every now and then. It's just hard to find a pair that are comfy and supportive enough - most of the time I just have my bits falling out at awkward angles, which kinda ruins the fun.
i have a thong that gets worn to work and i've gone commando before, i remember wearing my thong on a night out, getting on the dance floor in the early hours giving it some with my oh and some of her friends when one of them screamed - OMG he's wearing your thong! pointing at my ares, no its his came the reply from my wife.