Similar to the penis tuck. The swift tuck you do with your left (or non-dominant hand, leaving dominant hand to shake hands) when you're in public, standing up and have a visible erection.

Typically, thumb (under clothes) at the base of the erect penis and fingers at the head of the penis (over clothes). Then, push wrist down and fingers up. This results in the penis being tucked under the elastic strap of briefs or any such equivalent.

When done in one swift movement (that takes years to master) it appears that you are simply adjusting your pants/getting comfortable/scratching. This can be embarrassing but is better than the visibly erect alternative.

The act of pleasuring yourself while barely pretending to disguise the action from another person in the same space as yourself.

When you pull your pants up after taking a shit and your shirt is still partially tucked in on one side.

Referring to when a man tucks his head inward towards his chest in order to decrease drag while in an open wheel race car.

When a male tucks his penis in between their legs and plays, "just the tip" with their own butthole.

when you tuck your tit

To dress up toes like little dolls.