I am not offended in the slightest by your surprise at encountering a funny maths teacher. Most of our humour tends to be a bit calculated or rely on their audience knowing some theory or advanced mathematics. Plus Ofsted frown upon fun in lessons so few teachers risk it.
i once surprised a member of the management team. My year 11 class were drawing quadratic graphs. In case anyone reading this doesn't know they have a U shape called a parabola. To make it memorable I had got them to sing 'da dah da da dah' when anyone said parabola, to the tune of the Muppets.
pa-rab-o-la, da dah da da dah
we had a bit of a laugh, but they all knew the name for the shape of a quadratic graph!
ah those were the days! Mm