military slang for highly contagious virii such as colds, stomach bugs, etc. that leave a person with any debilitating combination of non-stop runny nose, coughing up heavy phlegm, vomiting, diarrhea, extreme muscle weakness/pain, etc. The "creeping" part refers to the fact that it seems to make its way through ALL of the ranks eventually.
It's cold and flu season now, so if you get the Creeping Crud - go on sickcall and make sure doc gives you Quarters, because the rest of us don't want it!
military "verbal shorthand" for "Confinement to Quarters," most often for medical reasons such as acute viral respiratory infections that are disabling and highly contagious but NOT so severe as to require any hospital stay.
I got the latest Creeping Crud, so doc put me on Quarters for the next three days.