When a guy confidently claims to know something, but in reality, he's just making wild stabs in the dark.
Often used to win arguments or to seem smart to impress the girls.
Tina: "Will we hit traffic on the way there?"
Bob: "No way, it'll be a smooth ride."
*Stuck in traffic for hours*
Tina: "Bob's guy guessing got us again!"
The act of spending an unnecessarily long amount of time preparing for a later event in which one wishes to look nice, for example, a party, pub crawl, or a trip of New Orleans during Spring Break. You then find that you've spent so much time making yourself up, it is too late or pointless to attend said event.