Working with immature co workers

I just turned 30. I work in an office. I have 2 co workers that are in their early 20s. One is a girl and one is a guy.

They act very immature. They say rude, inappropriate things. They make fun of most of our customers.

I feel like they pick on me a lot. If I call off, they make comments about it tbe next day. They just make rude little comments about everything.

I haven’t dealt with this since like middle school.

I can’t talk to my manager about it because she seems to like them. And she has favorites.

I’m just uncomfortable at work.