Straight male here, and I've been at the mercy of more than a few men. With guys, I've always been the 'Lee because, in my area, they aren't very ticklish or just don't like tickling.
They usually focus on my feet/toes because I'm most ticklish there, but I still get a few underbody tickles. Oh, and they've all discovered my insanely ticklish cock/balls.
I even compromised once and allowed one to just suck me off as long as he held me down and did it while another guy tickled and worshipped my feet.
Another intense experience was when I set up a meeting with a guy at a local motel for a glory hole. He had me lie down on the bed and was sucking me off when he started playing with my balls. Naturally, I started laughing and squirming, warning him that I'm extremely ticklish there. He thoroughly enjoyed it and didn't stop until he milked me completely dry.
So, all that to say: I'm a straight guy and I enjoy being tickled by gay 'Lers.