someone who does not use proper urinal ettiquette when there is more than 2 stalls, he's the guy who goes between and uses the middle urinal causing an uncomfortableness.
When Hawkins went to the bathroom he decided against proper ettiquette and decided he'd become a middler.
by GabeV March 16, 2008
one who prefers to fold his penis in half during intercourse in order to get the job done.
after jimmy drank a half liter of jack, he became a real middler when trying to do his wife.
by cunt boss September 04, 2012