The sense "a joke" derives from the practice of tapping one's toes to indicate pleasure; compare toe-tappingly.
The sense "closeted homosexual who solicits gay sex" derives from the 2007 Larry Craig scandal  in which then-Senator Larry Craig of Idaho was arrested after tapping his toes in a men's restroom,  an action seen as covert solicitation of sex.
toe-tapper (plural toe-tappers)
- A piece of music with a prominent beat, to which one feels compelled to tap their toes.
- A joke which is found to be pleasingly humorous.
- A homosexual who is closeted (regarding sexual orientation), especially one who solicits gay sex. [from 2007]
2007 September 18, Jody May-Chang, “Justice Dept. has guidebook to public sex”, in Pridedepot.com:
- The US Department of Justice has a handy guide for police to focus on when attempting to bust the next toe tapper or washroom wanker.
2007 December 12, David, “No fucking way”, in Joelderfner.com:
- Any bets he is an accomplished toe-tapper in the synagogue bathrooms?
2008 February 14, g1r8c7c6#702696, “Hola, Hillary”, in Caller.com:
- It was nice to use the public restroom at the Hillary event. I didn't have to worry about a republican toe-tapper being in the next stall.
2009 September 7, xavierob82, “VA GOP GOV Candidate Caught by his Family Values”, in City-data.com:
- Yeah, just like George "Mr. Macaca" Allen destroyed Jim Webb in '06. This race is still quite a way aways, and nothing gets Northern Virginia liberals out to the polls in full force faster than GOP nutjobs still peddling phony "cultural" issues and supposed "family values". This guy McDonnel, in fact, sounds like a bonafide bathroom stall toe-tapper.
2010 April 18, aristotle, “Sneaking a lesbian onto the Supreme Court”, in Expeditersonline.com:
- Look, if you got a toe-tapper in the stall next to yourself, just run.
2010 August 26, hill b. nut, “The Devil Made Me Do It”, in Blogspot.com:
- Letting him have a hand in gay politics right now is a little akin to letting the fox too near the henhouse. Or in terms that Republicans can understand, it's a little like letting the toe-tapper too near the airport bathroom stall.
For more examples of usage of this term, see Citations:toe-tapper.
- ^ Associated Press (2007-10-10), “Larry Craig's 'Wide Stance' Excuse Gains Prominence in Lexicon”, in FOX News
- ^ Michael K. Lavers (2007-09-11), “GLAAD After NY Post-Again-for ’Toe-Tapping’”, in EDGE Boston
- ^ Murphy, Patti; David Stout (2007-08-29), “Idaho Senator Says He Regrets Guilty Plea in Restroom Incident”, in The New York Times