1. We had a sleepover at Susan's house.

Question

2. We had a sleepover party at Susan's house.

(Which expression is correct? Are both grammatical?)

Q2: Do only girls have a sleepover? How about boys? Do they have sleepover parties? Do all teenagers have sleepover party in the USA?

Answer 1

Both are correct, but 1. is more common.

Boys also have sleepovers. I don't know about ALL teenagers, but certainly most have sleepover parties.