I dunno man, it doesn't bother me when it's a silly pun like this. But when I see vids of people outright laughing at people as they stutter, that does get to me. Like the character Jimmy in South Park. He stutters and the stuttering jokes around him are genuinely funny, and it doesn't feel as though they're punching down on the character. But if you're just downright taking the piss out of an individual in their most vulnerable moments, then that's just outright scumbag behaviour.