A variation on the classic teabag. Choose a victim who has passed out at a party w/ their shoes on. While they're snoring blissfully, gently rest your scrotum on their upper lip for a few inhalations, letting them draw your scent into their dreams. then, simply zip up and walk away. Subject will wake up and suspect something occurred, but never know exactly where that smell on their upper lip came from.
"I snouched him good." "He totally had that snouch coming."