I hate when people refer to orange juice as OJ.
Why OJ? Do you want to sound cool? Is it so much of a hustle to say orange juice? Do you abbreviate apple juice too? " Hey yeah, let me have some AJ?" - said by no one ever. I just think it sound annoying af.
Edit: I don't have any issues with abbreviations, except for OJ as orange juice. Sorry if I offended some of you with sensitive feelings.