crack someone up / crack up:
— My two year old cracks us up because he's so naughty and we try desperately not to laugh.
— Your dad's dancing really cracks me up. He's a big hip-hop fan I guess?
— The way my bulldog snores so loud always cracks me up.
— Who's your favorite comedian? Amy Poehler and Kristen Wiig really crack me up.
— I didn't want to laugh but the way my girlfriend painted on thick rectangular-shaped eyebrows for prom cracked me up.
— You should try to get in Mr. Roth's English class—he cracks us up all the time.
— We tried hard not to crack up when our teacher spilled coffee all over her books.
— Did you watch Saturday Night Live last night? I couldn't stop cracking up.
— My little sister's friends crack up at our older brother's jokes so he thinks he's hilarious but they only laugh because he's cute.
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