Anything non-Italian. Often used by Italian Americans, it is a bastardization of the word "American". Italian Americans hit the 'r' in a way that the listener might interpret as a 't' sound, and the 'c' in many words can be heard as softer, or with a 'g' sound. The 'i' in Italian is pronounced as a long 'e' sound (ee).
"American" was broken down as such:
Don't cut your pasta, or they'll think you're a metigan.