I freaking HATE when you order a coffee with alternate milk. Say a flat white with Oat. You say that to them. They make it and announce "Flat white?" and you go "With oat?" and they go "..... yyyyyyyyyyyyyyyes...." in a REALLY uncertain tone.
Takes all my effort to not lock eye contact and say "Cause bro, if it isnt, and I shit myself to death your gonna experience exactly what this will feel like when I get my hands on you".
People who don't repeat orders in full bother me, I like a supreme with extra garlic, don't say only supreme back to me. Also when I'm giving numbers over the phone... 931 uh huh, 334 uh huh, 553 uhh the computer says no.