When you don't understand something and you are super pissed.
When you don't feel like saying "fucking understand"
When fucking understand just doesn't quite display the needed emotion.
conspiring against an authority figure to take synchronized shits underneath said authority figure's deck. Usually performed in groups of two to five people. In extreme cases, shit burritos are fashioned with paper towels and left to be found.
Oh, no. Have you seen the kids? I hope their not underdecking us again!
The male genitalia being viewed from an upward looking angle. Similar to the female version of underboob but with a wiener instead. Also referred to as Australian dick.
I knew I was going to have a rough day when I woke up to my roommate giving me some undercock.
Your mom seemed pretty interested in me so I gave her a little Australian dick.