Indeed irritated feels when a co-worker who stole your idea and recognize that it is the result of personal thoughts. Instead of lingering feeling annoyed, you better take the positive side and still have brilliant ideas.
It would be better anyway if you do these four things:
When a co-worker suggested the idea that has been stolen from you, leave it alone and be patient. Over time these actions will be caught, too. Therefore, he will not be able to give a brilliant idea again continuously.
Rather than a protracted upset, you should take the positive side is to feel proud when your creative ideas stolen coworkers. It also shows that you do have a better ability than them. Keep working and have a brilliant idea.
3. Befriend fixed
Do not antagonize your coworkers. Keep friends as usual. That way, they will feel guilty for stealing your idea.
4. permanent Working
Theft of ideas in the office is not a stranger. This often happens when two people work together. If this is your idea has been stolen by a team of co-workers who do not stop to work with that person. Keep working properly and equally share and learn to improve capabilities.