Why do teachers laugh at me.?

Maybe someone sticks something on your back during the day. Try asking them what's so bloody funny. =P

Because they are trolls

Are you doing something funny?

You didn't put enough information up. How are we supposed to know why they're laughing at you unless we saw them do it?

I truly hope that no one is making an effort to make you uncomfortable. No matter what, you are person of value & worth who deserves respect. I would suggest turning to a trusted adult and sharing your feelings (a parent, trusted teacher or counselor). If someone is acting inappropriately they can help you by taking action on your behalf and dealing with it in a proper way.

This next part might not sound related, but it is. I like to golf and sometimes you play in front of a lot of people. It seems like everyone is watching, mocking you and waiting for you to mess up. In reality, they are so worried about doing well themselves they really aren't paying any attention to you. The world of school can be like that, too. Students are trying to figure out who they are and where they are headed in life. Sometimes, it feels like the world is watching your every move.

Try to think positive, make tomorrow a good day for yourself and reach out to someone you trust to get some help trying to sort this out. I really think everything is going to be all right and your hard times will soon be behind you.

Ha ha ha ha

This is definitely a problem that needs to be dealt with. Ask the school psychologist for an appt to discuss.
As a teacher, I am appalled!