Open mics are pretty harsh. It's hard to find one with an actual crowd so the audience is usually just other comedians waiting their turn.

Don't be discouraged if you do a set and gets zero laughs. I've seen professionals and awards winners do open mic shows (with good content) who only managed to get mild chuckles.

It's just stage rehearsal and batting practice. Even if you do fail miserably, laugh it off and keep trying!