Good question! I reeeeeeeeally don't know. I guess when I was twelve...around that time Mr Happy would seriously start to stand at attention whenever I performed an operation myself, or watched someone else pin some girl down and make her holler. I certainly never had a problem with it, but I never discussed it with anyone...
Oh, am I laughing right now at the memories!!! Here's one in particular...It was summertime, and I happily tore off some girl's flip flops, and went to work, letting my fingers do the walking, and when I was done, Mr Happy's ready to...well...cut diamonds. Well, I can't let this girl see THAT, can I? No way! So, as I'm getting up, I fake a backache, you know? "Oh, man, I hurt my back!" Naturally, the girl would be concerned, and you're in the hunched over position, waiting for...trying to MAKE Mr. Happy comply and retreat back to his normal position. Lasted a few seconds, at least. Eventually, he'd calm down, and you'd get up and everything would be OK, and the girl wouldn't be any the wiser. Thank God for that...
Those were fun days! I guess as I developed sexually into an adult, the tickling and the sexuality became somewhat inseparable, in a way. I like it like that....
