To ejaculate into a partners face through the use of a high power fan, rather than traditional means.

Speculation of the origins of the German Jetstream date back to WWII, where it was thought that Hitler would use the German Jetstream on Eva Braun. The use of this technique allowed him to taunt allied attacks with threats of Advanced German Jetstreams. It was believed to have been a plausible origin, as he was able to conquer europe by jizzing into a fan.
You're fucking a girl, and right before you cum you bring out a fan. You jizz into the path of the fan, thus hitting the females face through indirect means by way of the breeze. Afterwards you ask the female "how was that German Jetstream?"
by I Hate Kuwait 112 April 27, 2010
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