Meaning: Super totally cool
Cucumbers don鈥檛 seem to be all that cool. I mean, they don鈥檛 have BMX bikes, Kanye West glasses, or even know how to do the robot. But this expression is taken from a literal characteristic of cukes. The inside of a cucumber is actually 20 degrees cooler than their outsides. So even without some Ed Hardy gear, cucumbers are pretty cool.