It was sweltering in the dungeon from whatever Neville had put in his cauldron and it had made the room temperature jump to uncomfortable levels.
Moving away from his desk, Harry took off his outer robe leaving him in a T-shirt and jeans. Harry continued scrubbing the desk, trying not to mutter at the unfairness of the detention, once again he hadn't done anything. If Harry hadn't known better he would have thought Snape just like having him around.
Harry switched to the other side of the table, "Mr Potter!" Snape snapped barely on the safe side of dangerous.
Harry straightened, "Yes sir."
Wordlessly, Snape stood from behind his desk and pulled Harry bodily out from behind the desk. "Where did you get this shirt?" He asked his voice dangerously quiet.
"I found it when I went shopping last week in Hogsmeade. Why?" Harry replied, far too innocently.
Snape took a step back and re-read the slogan on the T-shirt.
It bright Gryffindor red were the words 'Suck Me'.
"Very well I shall."
The next day Harry wore another new T-shirt, he made his way potions Harry tugged it making sure it was straight.
This one said 'Fuck me'.
It was the first time Harry was happy to be given a detention.