Catpone Cerberus

I love when games have features that really don't need to be there but are because fun. 
I couldn't find a gif, but in Ultrakill, one of the variants of revolver has a secondary fire that makes you spin the gun, and this spin, has lift. You won't really see this in regular gameplay, like ever, but if you get enough "dual-wield" pickups (each give one extra gun) with cheats, spinning your gun(s) makes you fly.  

This was coded in, there is no reason for such feature to exist, but it does, and I love that.