A trend, an overly popular trend. Skinny jeans (or skinnies) are usually worn by your modern trendwhore, scene kid, sk8r boi, or emo people. In my honest opinion, skinny jeans make girls with no ass look like they have one. Guys who wear skinny jeans usually look like anorexic little girls, with a presumably small penis.
People who say they wear skinny jeans because they are comfortable and cute are usually lying, because, they're wearing them because EVERYONE ELSE DOES.
Trendwhore: LAIK OH MAI GAWD, I LAIK LUV MAI NEW SKINNY JEANS, DER SO CUUUUUTTTTEEE!
Sane person: Please, go kill yourself, you brainless puppet.