Calling the cops bluff

i had something similar happen recently. i won't tell the whole backstory, but the the cops asked me what i had in my book bag. i said "books, papers...oh and a steak knife because i used it to cut cheese at a work party today." he said "mind if i take a look?" i also had rolling papers and a grinder with cannabis residue in there. i said "i'd rather you didn't." the look on his face was awesome. so surprised. he retaliated with "well i can either look now or take you to jail and look anyway." i stood my ground and left with a ticket unrelated to marijuana