The re-usage of a condom that was previously used for anal sex.
"Yo bro do you have a condom I can borrow?" "yeah man, there's a stinky beanie in my drawer.
I had to use a stinky beanie on my girl last night.
I had sex with a stinky beanie on yesterday.
"Bro me an my girl did anal last night! Now we can do the stinky beanie in the morning!"