What Limits -
I also learnt from wikipedia that Pongo is the genus for Orang-Utans. Thats probably where it came from!
I was always led to believe that "Pongos" resulted from the Army going to war in grubby fox-holes etc & not getting adequate opportunity to wash. No specific criticism implied, just a statement of fact that "everywhere the Army goes, the pong goes"!
Readers should also be aware that the term "fish-head" is used by the Naval Aviator for
non-flying, specifically ship-driving, officers of the Navy, whereas the jocular term for the aviators by fish-heads is WAFU, as in "Wet & F***ing Useless"! WAFUs never like being referred to as Fish-heads, as an invitation to the bridge of a ship was often a pre-cursor to an unwanted interview with the Captain - WAFUs prefer the safety of their flight deck, normally out of bounds to anyone (especially fish-heads) not connected with their confusing, complicated, noisy and dangerous business of flying . . . and sunbathing!!
With apologies for digressing from the thread.