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.
The act, or process, of being a douchebag
. Similar to shenanigans.
My friends and I went out last night and french-toasted this guy's car, and engaged in other such douchebaggitry