So over the summer I worked 3rd shift in a gas station in my hometown, so I knew a lot of the people that came in. One of my favorite interactions was as follows.
I was in the middle of some boring cleaning chore or another when the little chime rang out letting me know the front doors had opened. I walked back to the counter to find my cousin waiting. The moment he sees me his face drops and I can tell what's coming.
Now I should mention at my gas station we keep small, easy to steal things behind the counter such as lighters, 5 hour energy, and... condoms.
He will be Mumbling Cousin, MC for short.
MC: Hey, could I get....(here he trailed off and I honestly couldn't hear him.)
Me: Sorry what?
He just gives me the death glare for making him repeat the dreaded phrase.
MC: I said... could I get a box of condoms?
We have a few different kinds so I walk back and ask him which kind he wants.
MC: just grab a box, I dont care what kind.
So I check him out and, while I have remained extremely professional and tried really hard not to laugh at him or make him feel even more awkward, as I handed him the bag I said my usual "have a good night." That set us both off laughing and he left flipping me off.(out of familial love of course.)