Fred wondered almost absently if Snape's voice coming up from behind him unexpectedly would always make the hairs on the back of his neck stand up like that. It was an unmistakable voice, after all, given the amount of times it had assigned him detention. At least he didn't jump - chalk one up for Gryffindor bravery, or something.
"Right, but his favourite customer shouldn't have to ring it," He answered, contradicting the word by smacking his hand on the little bell that was on the counter four or five times.