A word for a massive erection brought on at random by an unexplained sexual stimulator. Ever had an unwanted boner? Ever felt that your erectile tissue feels like shooting up and making a hole in your jeans? Whenever you get an unwanted stiffie and you can't explain why then you know you got a Uren.
'Jeez, I just got a massive Uren! Wish it'll go!
Doing an 'Ivan Aleksandar' (more commonly called an IA) is the act of flicking spunk/shit at people heads from behind.
Person 1 - Man what just hit me in the head??
Person 2 - Looks like someone's done an Ivan Aleksandar!