Fallergieson 

Canadian military slang for allergy-related frustration. Often related to poor timing of sneezes, coughing, sniffles, and other allergy symptoms; for example during inspection, while observing the enemy, or while trying to hide from the MPs after they bust your coke dealer.

Morty is on the OP and sees the enemy, but he finds himself in a life-or-death struggle to suppress a sneeze so he doesn't alert the enemy. He is experience severe and visible fallergieson.
"Man I had some serious fallergiesons during the OC's inspection this morning."

Fallergieson by tucanspam April 8, 2021

fallergies 

Various irritants that descend upon humans and plague them during the fall season. A combination of "fall" and "allergies."

I'm expecting the worst when the 1st round of fallergies hits me.

fallergies by Kamikaze Kool-Aid Man October 4, 2010