Peter is waiting in line for his coffee when he realises that he's standing right behind Blaine and Kurt. He has to restrain himself from tapping them on the shoulder and starting a conversation because,

A; he isn't in uniform and,

B; they don't know who he is.

Even saying Hi could be risky if they recognise his voice, so he stays silent.

"Fags" he hears the sneer to his left. He watches Blaine and Kurt, they stiffen but don't turn around. He thinks that they have far better control than he would have under then same circumstances.

If the homophobic jerk who uttered the insult is upset when he finds the seat of his pants webbed permanently to his chair ten minutes later, well that's just too bad.