If you're jumping over a ticket barrier you accept the risk that you'll be caught by security - not by your own dick.
So you've got to feel for the poor bloke whose attempt at dodging a train fare led to a barrier door snapping shut on his penis, leaving him screaming in agony as onlookers filmed the entire, painful ordeal.
A clip of the bizarre incident, which reportedly went down at the entrance to London's Covent Garden tube station, shows several London Underground staff members and a couple of British Transport Police officers working to free the unidentified bloke.
Some helpful advice yelled in the background of the video includes: "Get him some butter! Butter him up! Butter him up!" and: "No, oil, oil, oil!"
Eventually the man and his manhood are released from the automatic doors thanks to some interesting manoeuvres by a quick-thinking copper, who gets a hug from the very relieved fare-dodger.
While it's not clear when exactly the penis guy trap incident occurred, it's probably safe to assume that old mate will be paying full-whack on his train tickets from now on.