It's when someone in the relationship doesn't know how they feel and they ask for a break not to break up just a break so he/she can think about if they still wanna be in the relationship
When you're trying to play a song and you fail miserably. For reference, the can-can is a well known dance, and band directors often have students play it.
"Wow, you played so badly!"
"Yeah, that was more of a can't-can't than a can-can, know what I'm saying?"