A variant of "that's what she said." Instead of referring to sexual connotations, it is used to refer to spending a lot of money, making a mess, or fucking up very badly. Arose after the 2010 BP oil leak in the Gulf of Mexico.
X: Oh man, I really screwed the pooch on that one.
Y: That's what BP said!
X: It's going to take me all day to clean this mess up.
Y: That's what BP said!
X: I'm paying tonight. The sky is the limit.
Y: That's what BP said!
Y: That's what BP said!
X: It's going to take me all day to clean this mess up.
Y: That's what BP said!
X: I'm paying tonight. The sky is the limit.
Y: That's what BP said!
by Hamfry June 9, 2010
Instead of "that's what she said", but referring to an embarrassing situation, or something that one would rather cover up.
Buffy: "I don't want to go to the beach. I'm having a heavy flow day."
Heather: "That's what BP said!"
Heather: "That's what BP said!"
by jasonspsyche June 22, 2010