Mr. Badass is being tailed by Mr. Spy. Mr. Spy darts from shadow to shadow as Mr. Badass goes about his daily routine. He goes shopping, chats with some friends and then walks into an alley supposedly for some secret business. Just then, without facing Mr. Spy, he calls out, "Sir, you've been hiding all day. Why don't you show yourself?" Mr. Badass just pulled a Badass Spot Check. A Badass Spot Check can be performed many ways. A man could also be traveling in a group and suddenly halt everyone and whisper, "Be on your guard! We're not alone." This trope does not apply if the person tailing him does something to give away his position, like trip and stumble into view. It is important that the person being tailed gives no sign (to his follower or the audience) that he is aware he his being followed. The audience should be just as surprised as the tail that the man was aware of his presence. If he's less of the honorable sort, he can perform his Badass Spot Check by firing/throwing a projectile at the spot where the tail is hiding instead of calling out to him. If he is a trickster, he can refrain from revealing that he spots his tail until after the mission, by tricking the tail into steal a fake version of whatever he was after. Examples: In "Uncharted 3", Victor Sully performs one on young Nathan Drake after being tailed all over town. Done twice in "Blade of the Immortal", first by Annotsu to Rin when she covertly watches him train, second by Kasekage, again to Rin, when he mentions that he had been aware of her spying on him every day. Done in "Rogue Galaxy" by Seed to Jaster and his allies as they spy on Valkog. Without looking, he says, "We are being watched." In "Red Cliff" Zhou Yu plays dumb and pretends not to suspect one of Cao Cao's spies. He has a "secret meeting" where he discusses false battle plans with a subordinate within earshot of the spy, and later pretends to get drunk and allows the spy to steal a paper from his pocket that falsely incriminates two of the enemy officers as spies. Throughout Afro Samurai, the eponymous character is fully aware of when he's being watched by a member of the Empty Seven Clan. When he's defeated most of them, he proceeds to kill the one who was watching him by shoving his own binoculars into his head. In The State Counsellor, Mr. Green and the Needle, both experienced terrorists, have an uncanny ability to detect police agents tailing them. Keith Mars from Veronica Mars pulls this off several times, most notably the "trickster" variety to the Russian mafia in the first season. He drops his car off at a hotel, gets the mobsters to follow him inside, doubles back to the mobster car and breaks in to take a look at the documents in the glove box to figure out why he's being tailed. And he gets away with it. Subverted in Hanaukyo Maid Tai La Verite episode 4 "Konoe Rises". When Taro goes into town to do some shopping, his bodyguard Konoe Tsurugi stealthily shadows him. At one point he's looking in a store window and calls out to her. Later on she asks him how he knew she was there and he says he didn't know, he just assumed she'd follow him.
Hello, Unknown Troper. You'll need to get known to lend a hand here.