His girls clapped

Alright listen up, buttercup. So, basically, this Harry dude's "girls" (probably his fangirls or some backup dancers, I dunno, you wouldn't know) clapped. Big deal, right? It's just a short statement. BTW is a short-hand for "by the way". This is probably a caption to some image or video and by itself it's not funny at all! You are not smart.