trojan finger
When a dude tells his girl he's only inserting his finger(s) into her vagina or asshole but after getting her good and worked up he slips his penis in and quickly ejaculates before she realizes he's tricked her.
Owen was fingering his girlfriend so hard she didn't notice he had slipped his cock in until he had already dumped a load inside of her. When she panicked and asked him what he was doing, he proudly explained he was pulling a trojan finger on her.