Much of the fighter pilot lexicon is not suitable for the ears of Mom or the kids.  When translated, this is one of those terms.

YGBSM is short for “You Gotta Be Sh-tting Me,” which is obviously a term of shock, disbelief, or resignation at a realization of institutional stupidity.  Where did it come from, and why is it so popular in the fighter pilot community?

Lt Col Allen Lamb, USAF (ret.), wrote a first person account about being one of the Air Force’s (the world’s) first SAM-killers, otherwise known as “Wild Weasels:”  

[My EWO] Jack Donnovan’s contribution to the vernacular when introduced to the Wild Weasel concept was more enduring, and became the semi-official motto of the Wild Weasel profession: YGBSM – “You gotta be sh-tting me.” This was the natural response of an educated man, a veteran EWO on B-52s and the like, upon learning that he was to fly back seat to a self-absorbed fighter pilot while acting as flypaper for enemy SAMs. What would you say?

(The first “hunter-killer” teams were F-100s and F-105s. By Operation Desert Storm they were F-4s and F-16s. Now the role is flown solely by the single-seat F-16.)

That the phrase has endured over the years is more a testament to fighter pilot irreverence than anything else.  Then again, the fighter pilot patience is notoriously short, so the phrase has certainly seen near-constant use since it started.  Like the US Air Force Academy’s BOHICA and IHTFP, it is a “clever” and underhanded way of making a (crude) point.  The military has been using acronyms like this long before teenagers learned to type “LOL” with only their thumbs.

Which is why YGBSM keeps appearing in the most unusual places.  Naturally, there are the unit patches.

Then, interestingly enough, the photographer for an Air Force-credited photo (used at the Air Force Times) must have missed the patch.

The best, though, might be this display at the National Museum of the US Air Force in Dayton.

The display sits in front of the Wild Weasel F-105 in the Southeast Asia War Gallery of the museum; this photo is even on their website.

When things like this show up in public and prominent places, its difficult to know if it was an innocent and ignorant person just picking a picture that popped up on a search, or if a fighter pilot picked this just to have a secret joke with his fellow aviators.

Despite its relatively short history, the fighter pilot culture is rich in (irreverent) tradition, much of it encapsulated in the fighter pilot vocabulary that makes up a language all its own.

See more Fighter Pilot Speak here.

Wikipedia has some information on this topic in their “Wild Weasel” section.