look up any word, like b4nny:
 
1.
Marathon sex between two sexually athletic people. More than 12 hrs of sex-n-rest. A couple who tries to see how many postions and places they can climax in a given day, weekend, or timeframe.
Every time we've ever had sex it's always led to a fuck-a-thon. It takes me a week to recover. His rebound time is less than 10 minutes.
by Jolie St. Laurent April 09, 2006
 
2.
an event where a guy and a chick get it on repeatedly, as if they're never gonna stop
"How was your date?"
"Lasted all weekend, a real fuckathon.I was exhausted by Monday morning, glad to go to work."
by Jake March 15, 2004
 
3.
1. similar to marathon just with fucking
2. can be just continous sexual contact between a man and a woman
3. 3-some, 4 some, 5 some, etc (when u get the "buds" together and they arent weraing any clothes except perhaps a tie)
hey i went to a fucka thon

man i was tired after my 36 hour fuckathon with marissa

man lets get bob, cally, merry, dolly, and mark togehter so we can all do each other up the ass
by BHUDDA'S FRIEND June 02, 2005
 
4.
a long session of sex.
Chick 1: Girl, where you been all weekend? We was supposed to go to the movies.

Chick 2: My bad girl, me and my man was having a fuck-a-thon.
by SweetPeaches404 January 25, 2009
 
5.
When people indulge in sex for longer periods of time, usually over the weekends and in groups. Gays regularly engage in fuckathons on weekend.
Mark: "Boy my ass is sore and I can's hit; it took 20 loads this weekend"
Eli: "Man, you were in a fuckathon"
Mark: "Yes, I was and it was one helluva experience."
by shmuzzy February 27, 2010