The swarm of humans in town for the same trade show
They all have the same laminated pass hanging around their neck, and there's one woman for every 14 men in attendance.
The person trying gelato for the first time
It's served in every hotel lobby, so it must be good, right? You'll never go back to regular ice cream again.
The bachelorette party
After checking out Chippendales or Thunder From Down Under, these girls are ready to hit the Strip and let guys buy 'em drinks. If they're really doing things right, they've rented a long party limo for the night.
Dude selling a bottle of water for a buck out of a cooler
Totally needed. Fair price. No complaints.
That guy who doesn't normally spend this much on dinner
... and is calculating the running total in his head every time something is ordered. "How many drinks was that? Do we really have room for dessert?"