An excessively large or thick makeshift toilet seat cover constructed from very many interleaved strips of toilet paper placed around the seat rim. So called because of the resemblance to the nest of a very large bird.
Created by persons using a public toilet who cannot bear to have their buttocks touch the seat when a disposable cover is not available, or though to be too small, thin or flimsy to be effective.
Usually seen by others when the creator leaves the construction un-flushed and in-place on the seat after departing the public restroom.
Someone at my office keeps leaving a California condor nest in one of the stalls! I wish they'd flush the damn thing when they're done.