after sitting for a short or long period of time then standing up will most likey get you a head rush, a rush of very extreme dizzyness.

to sport a boner, fly the sail at full mass, rock hard, etc.

When the brain does not recieve enough oxygen because of sudden changes in blood pressure. Its common to happen if you smoke some really potent marijuana and rise up too sudden. You may feel lightheaded in the beginning and experience some dimmed vision. In severe cases you may see alot of "stars" and have even more dimmed vision and it can be really intense and often leads to a panic attack. It may last up to 10mins or more. The only way to avoid this is too maybe eat something before you smoke or dont smoke so mutch if it is really potent.

A headrush is a feeling of light-headedness. Headrushes usually happen if you stand up after sitting down for a long period of time. Your field of vision shrinks temporarily, and it looks like you're blacking out, but it only makes you dizzy for a few seconds until the feeling wears off.
Headrushes can cause some embarrassment, because they occur on a slight delay, so that you're already far from your chair when the feeling kicks in. If there's a table or wall nearby, lean on it for support just in case. Otherwise, just sit down or stand there for a few seconds.

If you are prone to skip meals some days, or don't get enough sleep, you are more likely to get headrushes. Frequent headrushes are crazy as hell, but get old pretty quickly.

smoking just enough weed to feel the changing in the weight of your head, but not yet stoned. You sort of begin to feel you head go heavy, light, and so on... a pleasant feeling

When a horny chick runs full speed at a man to give him head.

Erection that catches you offgaurd, normally triggered by extremely attractive women.