Know What I Mean?
"She said she was 30 years old but she acted 18, if you KWIM."
Stands for Know What I mean, unknown origine but quickly spreading around the web. Is related to kwym which is pronounced exactly the same but stands for know what you mean.
Guy : Hey man that french test was like saucy kwim
John : No I really don't know what you mean
Guy : Hey man that french test was like saucy know what i mean
John : No I really don't kwym