when you don't just have a cold or just have allergies. you've got both! an aggresive combination of both and a total bitch to get rid of.
As used in a simple dialogue,

"Paige, my nose is so itchy and I'm sneezing all day. The zyrtec and nyquil didn't work, so what's wrong with me?"
"Courtney, you have callergies!"
by wanna_be_WebMD August 26, 2013
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