(in a medical setting) the patient you know is faking so hard that it pains you to look at them, much less hear them speak. The 'ain't no body sick like me' person. The person who thinks they need antibiotics every other week. The person who is clearly not disabled until you look at them.
In the lobby the patient was smiling and flirting with the pretty girl next to him, however when the nurse called his name to get his vitals he suddenly looked pained, demonstarted an exaggerateddifficulty with walking and acted as if he couldn't even stand on the scales without assistance. The 25 year old oofer now needed his mommy.
Oofer means something good, it's the opposite of it's close word "Oof" which means something bad, the word oofer origins from the oof which characters in roblox create upon death.
That play was such an oofer!
Nice job bro, that was a nice oofer