The briefest possible act of sexual intercourse. There is no "pumping" involved - just insertion, ejaculation, and withdrawal.
Although very similar physically to a "one-pump wonder," but a flu shot is different because it is a deliberate act meant to save time. A flu shot requires training to accomplish correctly. A flu shot is a valuable scheduling tool.
Men generally enjoy giving flu shots more than women enjoy receiving them, but with discipline women should be able to train their bodies to orgasm from a single flu shot.
I joined the mile high club when I gave my girlfriend a flu shot in the bathroom right before the plane landed.
An important source of aluminum, necessary for the normal development of Alzheimer's, in the ever less elderly.
Not too worried about formaldehyde, mercury and aluminum, Eduardo got a flu shot, to gain a very small chance of avoiding a trivial, transient illness.
When you've had enough of someone. So you take a pen and preferably stab them in the eye or somewhere else on the body.
"Man this customer wont stop fuckin' complaining about this bread. Imma give em' a flu shot!"