Unique Unusual
# Quality Glitches
Unique Unusuals were created due to a bug introduced into TF2 with the Scream Fortress 2016 update. The nature of the bug was that any Unusual uncrated at the time had a Unique quality instead, with the unusual effect still attached.
There were ultimately patched by Valve, and every 'Unique Unusual' was reverted to an Unusual quality.
Source
Whoopee Cap
Team Fortress 2 Level 13 Hat
★ Unusual Effect: Tesla Coil
You'd have to be a jughead not to realize this cap is the pinnacle of fashion for the discerning youth.