In Russian, when a person mixes something up, they can jokingly say "mixed it up with the right angle" (перепутал с прямым углом).
This comes from an old joke:
"Water boils at 90 degrees."
"Sorry, but the textbook says water boils at 100 degrees!"
"Oh, you're right. Mixed it up with the right angle."
Is there a similar catchphrase in English?
"Hey man, check out that Scottish singer, Andie MacDowell, she's so cool!"
"Dude, Andie MacDowell is an American actress. Did you mean Amy MacDonald?"
"Oh you're right! _____ ! (Mixed it up with the right angle)"
Update: I'm not looking for a vocabulary term, but rather for a universally known joke, an ironic expression which is used to complete the statement. Something similar to "... and Bob's your uncle" or "... is the Pope Catholic?", but applicable to this situation.