What's 35 foot long and smells like piss? Line dancing at the senior citizens home.
I don't think that's funny. Are you trying to make a joke about older people?
It's just a joke, don't take it seriously.
You shouldn't joke about old people dancing. It's okay for older people to enjoy themselves and have fun.  You should let people be happy instead of trying to turn their joy into a harmful joke for your benefit.