A man's act of hiding his erection by flipping it up and tucking it into the waist of his pants. You flip tuck to conceal your boner, just like people conceal their flaws with a Nip Tuck.
Jim: "Did you see that hot ass girl on Nip Tuck last night?"
John: "YES! Holy shit, I had a boner all day. I had to Flip Tuck every time I left a class!"
A maneuver used by adolescents and men alike to conceal their erections; consisting of a "flip" where the shaft of the penis is freed from its initial position (generally running along the leg) and a "tuck" into the belt loop to secure the penis in its rightful place, centered between a man's legs. The fliptuck allows a perv to hide his shame, should he be smooth enough to pull this one off. The ideal fliptuck would occur through the pocket, although it is not uncommon for someone to reach straight into their pants and adjust their penis.
Corey's sister gave me major bonage when she rubbed up against me the other day! I had to pull the fliptuck so no one knew what was going on.