With a last ditch effort to avoid a shot in the mouth, the lips are tightly closed and are then covered with semen, resembling the white beard of Gandolf.
That trick was such a prude last night I ended up giving her a Gandolf all over her face.
Whenever a girl and a guy are fooling around and things get very hot but all of the sudden she stops foreplay and does not allow penetration. Obviously the guy stops after her "Thou shall not pass!"
When a character from a movie, book, or video game comes back into the plot, after appearing to have died, like Gandalf did in the movie series, The Lord of the Rings.
(also known as Pulling a Gandy)
Man, I really thought that a someone would be Pulling a Gandalf in that movie.