Female characteristics (although not really random) that get me going are:

Puffy nipples visible under blouse.
Back dimples.
Long athletic legs.
Blondes with a tan.
A slight overbite!

Truly random things that are turn ons:
Bananas
Sunny-side up eggs
Hotel rooms.
Fresh, clean white sheets
Silk
Sleeping in a tent in the middle of the woods.
Blind folds.