Tongue-in-cheek

Tongue-in-cheek means that you are not saying something seriously, and you are actually making a joke or being sarcastic. It's like when you say something that is silly, but you don't really mean it. For example, if someone asks you if you want to do your homework, and you say, "Oh sure, I just can't wait to spend my free time doing math problems!" you are being tongue-in-cheek. You're not really excited about doing homework, but you're making a joke to make people laugh or show that you don't want to do it. It's called tongue-in-cheek because when you say something like that, you might stick your tongue in your cheek, like you're trying to hold back a smile or giggle.