An illness which inevitably sets in when one returns home from attending a music festival.

Causes include:
-Between 2 and 10 hours sleep over a five day period.
-Living in your own dirt.
-Shouting and screaming a lot.
-Excessive consumption of both legal and illegal substances.
-Being too tight to buy food and hence going without for five days.

Unfortunately, due to the self-inflicted nature of this illness little sympathy can be expected.
Is Louise coming out tonight?
No, she's got festival flu.
by George15 January 20, 2008
Get the festival flu mug.
There are two main types of festival flu.

The first one is the Music festival flu. Which usually hits post event and is caused by the lapses in personal hygiene, diet and altered sleep patterns that can occur during a music festival. This type of festival flu is self inflicted.

The Second type is the Comedy festival and Fringe festival flu. This type caused by night after night of attending late night events in close approximation with many other people with similarly lapsed immune systems due to varying factors. While it is most common for this to be a post event flu, it can often crop up during the festival as it spreads. And it is important for people with festival flu to keep their distance from and refrain from shagging the festival performers as they cannot afford to lose their voices.
Comic: Hey there, care for a drink gorgeous?

Fringe dweller: I'm sorry I can't I have festival flu.

Comic: Oh... I better keep my distance. Some other time maybe.
by Figments October 13, 2011
Get the Festival Flu mug.