Alpha Phi Omega=I usually use APO. I did have someone give me a hard time about that once, a while ago..."Your name is not Alpha Pi Omicron, so therefore APO is INCORRECT!"
If there is a nasty nickname for us I haven't heard it.
Lambda Omega Pi=LOPi.
I just remembered something. Before I started IU, I got a book called The Right Foot. (an unofficial guide to IU) It said that AEPhi's nickname (though it could have been Alpha Phi's...I don't know where my copy is to check!) was Phisters. I've never heard anyone else call it that though. Has anyone else heard it or might that have been something just for the IU chapter?