Never! In order for that to occur, Moon, Earth and Sun would have to be perfectly aligned. However, if all them are aligned, it would create a total eclipse of the Moon!

Full Moon

Nevertheless, two among my four fans (yes, I have four children) tell me that one can see, indeed, an absolutely "full" Moon. It's enough to stay right at the center of a total eclipse of the Sun, because the Moon will be fully iluminated by the sunlight reflected by the Earth surface. It would be an unusual Full-New-Moon!

New Moon