I dont know about Twitter's rules, but I do know that AOL has a Terms Of Service mandate, which is what caused me to join TMF in the first place.
When I first got this computer, in May, 2002, I went into AOL chatrooms, and asked a couple of girls if they were ticklish. Next thing I know, I got a Terms of Service warning from AOL, saying something about "Inappropriate discussion in their chatrooms", and if I did it again, my service would be cancelled. So, I typed in keyword "Tickling", found the TMF, and I've been here ever since.
The only other place I would talk about tickling besides the TMF, would be in either a foot fetish, or other type of bondage, chatroom. Those are fetish orientated chatrooms, and it's highly unlikely one would get booted or banned for asking tickling questions. As for Twitter, I wouldn't do it, as they might well have the same Terms of Service rule as AOL, and one could be asking for a problem if someone you ask the question to complains to Twitter.
Mitch