A chaperphone is a good friend who can't come along on a date or other activity, but will call you or text you at least once, but often multiple times, to make sure you're not in trouble.
I have a blind date tonight, and I think it's going to be awful. Will you be my chaperphone and call me or text me at 9 so I have an excuse to leave? or... I know I'm married, but I want to hang out with this hottie tonight. Will you chaperphone me every half hour so I stay out of trouble?