I can't get behind that - You're saying no to something because it's stupid, it's bad,

You're saying no to something because it's stupid, it's bad, or it's just not worth your time. You're not even mad, you're just done.

'I can't get behind that rumor. It’s worse than my ex’s dating life.'

'I can't get behind that song. It’s like listening to a toaster sing opera.'

'I can't get behind that idea. It’s like trying to teach a goldfish algebra.'