A contraction of "issues internalized" - "sues in." Used to connote that a person is surpressing a lot of emotional baggage.

don't name your child susan, they will get a hefty slagging and will more likely be the only susan in their school. even though its unique its embarassing

A name you give to that one annoying bitch that's always getting on your nerves for sticking their nose into business that doesn't concern them.
It is commonly used on Social Media.

Susan is bitch who steals your toilet paper

Me: Susan who do you think you are? do you think you can really steal my last roll of toilet paper? I let you stay at my house for weeks ? do you think this is a free hotel?

Susan: oops

Me: Fuck you

made for my bitchy friends

Susan is the most passionate person you will ever meet. Her passion and love is not for people or animals. It is solely and exclusively a love for the Florida State Seminoles. She would sacrifice her youngest niece to help the Seminoles win on game day. When she prays, she secretly prays to her God Bobby Bowden. You will find a shrine in Susan's bedroom of all the greatest FSU players including Neon Deion Sanders, Warrick Dunn, Sebastian Janikoswki, Charlie Ward, Jameis Winston, Lee Corso and even Burt Reynolds. Her favorite colors are garnet and gold. She works out by doing no less than 2 hours of tomahawk chops daily. She will unfriend you on Facebook if you root for the Gators. When she dies, her tombstone will read "Gator Hater". Make no mistake, Susan is in love with FSU.

A girl who has an inny belly button that goes so in that it comes out the other side again.

Susans are VERY bad noodles. (lilsimsie reference)