Back in the 60s we had a pilot on 12(B) with the aptly named initials JB. This character, and he was, sported a magnificent bushy, full moustache. The snag was it was impossible to get a seal on his Oxygen mask.
Anyway he would try and the moustache would sprout up out the top. Periodically he would give in and shave it off. Periods of shaved and unshaved coincided with the opposite period on his security ID.
His subsequent posts to Antarctica, Oman and back to Antarctica gave him amply time to enjoy his 'tash.