Waddiwasi

Waddiwasi: Shoots a wad of gum out of a keyhole.

Uses
Remus Lupin considers this to be a useful little spell. He used it to remove a wad of gum from a keyhole that Peeves was putting there. The gum then shot up Peeves' nose.

The "useful spell" that Remus Lupin was showing them was undoubtedly the "wasi" part, in this case with a target word attached, "wad." Again we see how important intention is to magic, since the wad was directed into Peeves' nose by intent with the "go there" part of the spell. In another situation, the spell might be "stolawasi" to send a robe into a student's trunk, but it would only work if the student focused his mind on where he wanted the robe to go.