Similar to think it over, but usually applies to matters relating to those of the opposite sex.
When unsure of weather to sleep with a girl, it is best to wank it over for the clarity of mind one recieves apres-orgasm.
You can then ponder the matter without hormones getting in the way of logic. Who may be hot when you are randy might actually be horrific, and you only see this after beating the bald bishop.
STDs, ugly features, weight problems or even gender may be overlooked pre-ejaculation.
This procedure can also be a good remedy for beer goggles