When someone (usually a girl) plans on shacking with someone of the opposite sex, but doesn't want the other person to know she planned on staying over, she packs strategic items in her purse, such as a contact case, make-up remover, toothbrush, maybe even flip flops.
Variant on the common term ‘cradle snatching’ for someone who is sweet on a much younger honey. If you are not in it for the long haul but simply want to sample the youth for a short while, you are ‘cradle snacking’.