Culo Seco
Literal Spanish for "Dry Ass"
Noun - Someone who is uptight, has an attitude. Similar to saying in English that someone has a stick in their ass. 
"Mira esta culo seco" - Look at that asshole

"Tiene culo seco" - He has a stick up his ass.

"Que pasa, culo seco?" - Whats up, douchebag?