Recently, I went out dancing with some friends. I was dancing with one of the guys in the group and he asked for some tips on how to be a better "lead" on the dance floor. I told him one of the first things he could do was use a firmer grip on my back to guide me. (Side note: too many guys have "limp hand" when dancing and it's a big pet peeve of mine.) I placed his hand low on my shoulder blade and told him to keep it firmly there.
He tried to follow my instructions, but inevitably his hand would lose grip and drift to the side, leaving me with little guidance through the dance. Finally I looked him in the eye and said "Ok, this may be awkward for you, but I want you to find my bra strap and put your hand on it and keep it there."
He appeared startled at first, but then quickly replied "oh I can do THAT!"
And henceforth the "limp hand" problem was solved.