When a pair of jeans makes a girl appear to have a penis.
A Jeanis is when a girl is wearing a pair of jeans, which consequently make it appear that she has a Penis. If you are a girl, and especially if you grew up in the 90's, then you have probably had at least one Jeanis in your life.
The unfortunate protrusion of excess pant material when sitting, resulting from loose-fitting pants. Often mistaken for an erection by passers-by; may result in mockery, flattery, or just plain embarassment.
"Wow, nice jeanis you've got going on there, Tom"
"Shit! These pants are the worst for that.... or are they....?"
The small bunch of denim located at the zipper region of women's jeans that are a little too tight around the waistband, giving the illusion of male genitalia. It occurs mostly when the wearer is seated.
These jeans look great when I'm standing up, but they give me a jeanis when I sit down.