A phrase often used to sound empathetic when in most cases the scenario being discussed is too unique for the other person to have possibly gone through the same situation.
Person #1: Dude you won't believe this, but I saw Jeremy on my flight! I have never seen someone I know at the airport let alone on my plane!
Person #2 Yah, I hate it when that happens.
Person #1: What?!
The act of getting your pubes stuck under your helm.
Jamie has a short penis and long pubes and thus had a case of 'I hate it when that happens'.
by Matt G June 7, 2004