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’.
A person who taps people significantlyyounger than he/she is. If X is the older person's age then they are a cradle robber if they date a person who is less than half of their age plus 7 years. But for this function to work, X must be greater than or equal to 18. (Y = .5X + 7 X:18,infinity))