if people who are sitting or standing together squash up, they move closer together in order to make space for someone else
If we all squash up, there'll be room for Christine.
phrasesquash up squash up to move closer together in order to make space for someone or something else: Football fans were forced to squash up as a record number of people attended the match.We can get four people on the back seat if you all squash up.
squash up
To crush, crumple, or mash something into a broken or untidy state. A noun or pronoun can be used between "squash" and "up." Don't just squash your clothes up like that while you're packing—everything will be wrinkly when you unpack it later!The bully came over and squashed up my science fair diorama.
squash someone or something up
to grind someone or something up; to mash someone or something up. You had better stay out of the traffic, or some big truck will squash you up! The truck squashed up the tiny car.