to have a urination go really bad for whatever reason. Includes spraying urine everywhere because you tried to piss with a chubby, or having your urine shoot out at one or more 90degree angles due to being gum shut, or any other bad thing happening when you're taking a piss.
Combines 'piss' and 'disaster'.
Dude1: What the fuck happened in the bathroom?
Dude2: It was dark and the lid was down -- a classic recipe for pissaster.
Dude1: Well fuck, clean it up!
Missinterhearing is when someone says something and you don't quite hear what they have said, but instead of asking them to repeat it you respond with what you think you have heard. Old people are known to do this frequently.
Housemate A: It's three days till we get internet!
Housemate B: WHAT? Did you just say that there are three days till we get INTIMATE? What the hell!!!
Housemate A: Dude, you totally missinterheard me.
Person A: Tonight I'm going to wear my sluttishly high heels...
Person B: What on earth are Cottage Pie Heels??