When I was still in the Print trade, I worked in a sheltered workshop for people with disabilities, teaching them basic printing skills. (Ironically, that is where I met my girlfriend, she was one of the workers, and we have been together now for twenty years!)
Anyway, I had to go on a course in BSL, as we were employing some deaf workers, and I got Stage 1 certificate in BSL. However, as there are certain technical terms used in printing, we had to 'invent' a few signs for specialist words, but overall we got on fine. I actually found that I learnt more sign language from conversing with the workers than I learnt on the course.
Eventually, I got to the point that I could crack jokes with them in sign language, mostly obscene of course!
FWIW, sign language is always a good thing to have in your locker, you never know when you might have use for it.

Roy.