it isn't funny

1. I'm being serious; don't treat this like a joke. It isn't funny, Dave. You could have gotten hurt, do you understand? It isn't funny, Ron—we were all counting on you! Dude, it isn't funny! If I get caught, I'm gonna be in serious trouble with my parents!

2. Stop laughing at me; the situation is not humorous for me. Hey, it isn't funny, guys! How would you like having to go around school all day with a big rip in the seat of your pants? Why are you laughing? You really hurt my feelings, and it isn't funny! A: "It isn't funny!" B: "I mean, you're fully clothed and soaking wet—it's kind of funny."

3. Used at the end of a statement to indicate the extreme degree to which something is true. Just a few years back we were struggling to make ends meet. Now we've got so much work it isn't funny! Wow, Lauren's new boyfriend is so hot it isn't even funny! Life with a newborn is no joke. My wife and I are so exhausted, it isn't funny.