Is it normal to sing sentences?

When I'm in a good mood or around certain people I just want to annoy or make laugh, I add a specific rhythm to my sentences and draw out the last few words on high notes! Especially if I'm making a reference to something random or stupid! It's so much fun to do!
Also, my mind wanders a lot and I often just catch parts of a conversation (between me and someone or two other people) and they stick in my head - I realise I haven't been listening and just sing out what I heard while giving a funny look!
It's great fun!

Anyone else do this?