illegitimate invitation
Issuing an invitation which the other person can't accept, in the hope that you get credit for asking but don't have to follow through.
J. "Wanna go to dinner?"
N. "You know I gotta babysit my sister's 4 kids! That's an illegitimate invitation!"
N. "You know I gotta babysit my sister's 4 kids! That's an illegitimate invitation!"