When your exhaust (insert any other car mod or apply to anything that your significant other finds annoying and makes you get rid of as a result) is too loud for your wife and she demands that you remove that thing or else...
Kooper is a modern name for a male. He is all around great, and very friendly. A true ladies man. He is very athletic. If you're friend is a Kooper you have no idea how lucky you are! But you better not make him mad.