A year ago my husband and I went to Greece and I know I told him about 4 times that non-prescription codeine is illegal there. I left my small stash of tylenol-and-codeine tablets that I buy in Canada at home. Dear husband walks up to Immigration with the corner of a plastic bag peeking out of his shirt pocket and the Immigration officer says, "what's that?". My husband cheerfully pulls the bag of pills (mostly vitamins but also including his stash of Vicodin just in case of back pain) and says, "They're my vitamins". Aargh.
It's a good thing he's 68 and conventional-looking.
Don't try this yourself.