The difference a comma makes
Dance on, Grandma.
Infers that you are encouraging your elderly relative to continue her walker-bound version of gettin’ jiggy with it. (Apologies for mental imagery)
As compared to:
Dance on Grandma.
Infers that you are encouraging an Irish jig whilst trampling your elderly walker-bound relative.
Take three seconds to look up and learn how to use a comma. The world will thank you.
Or at the very least, your grandma will.