I am American and could care less about football, it does limit a lot of guy relationships if you don't care about watching sports. Playing sports is so much fun though, and a way better way to meet people.
“I could care less about $THING” and “I couldn't care less about $THING” mean the same thing. Each means that the speaker does not care about $THING.
That being the case, guy conversations that start out, "Hey, did you see the game last night?" typically end in awkward silence when I say, "No."