Inventions that make you say "well...duh."

[MyGodWearsAHoodie]

I don't see the beer cup thing as a "well...duh" the way I do with self adhesive stamps or upside down katchup bottles. 

I see it more like a "ah cool, but why do I really need this?" like I do with the machine that beats an egg while it is still inside its shell. 

[Jim Gray]

I've been told a good beer should be poured into the center of the glass.  You want the beer to get some oxygen and release some of the carbonation. Trying to eliminate the head by tipping the glass is a no-no. 

But since this is a concession stand selling Bud and Bud Light, I'm not sure the taste would be degraded by having the staff drink the beer first and then piss it back into the cups.

[Pappy13]

But since this is a concession stand selling Bud and Bud Light, I'm not sure the taste would be degraded by having the staff drink the beer first and then piss it back into the cups.

I believe this is referred to as "warm filtering" in the industry.

[StL FinFan]

They charge an extra fee for that.