An acronym for: I've Known You Since Pre-School.
Pronounced 'icky-sips' , can be used if you wish to obtain something from someone to whom it applies. This could be a material object, food, knowledge or being told a secret or embarrassing information.
"Can I have one of your cookies?"
"Ah man, I just gave a load away!"
"Come on, IKYSPS"
"What did she tell you?"
"I can't tell you man sorry"