Egging someone else's property, usually a car, then covering it with slices of bread, and leaving it in the sun. The sun cooks the eggs, baking the bread and ruining the car. Hence, french toast.
The Principal gave me detention the other day, so me and Pablo French Toasted his car.
A nasty person who resembles frenchtoast... usually has the following attributes: greasy hair-syrup, bad smelling-burnt eggs, baby powder in hair to try to cover up the grease-powdered sugar. May also be a mysterious whore-nobody knows where it came from and is everywhere.