Birna is the little things that get stuck between your toes. The word was invented in 2003 when the person Birna bought new socks, and got lots of stuff between her toes, and everyone made fun of her by saying "oh no.. Look at all this birna I have between my toes". It got more spread around the world, and now it is common known that birna is the word for stuff between your toes.
"Man, I've got lot of birna in my toes today!" or "Yesterday I had to pick out alot of birna between my toes.."
by helle hakkebakk February 21, 2009