The Canadian Pepsi Can
I came across this the other day. Well, I was searching it out after hearing that someone had just designed a two-holed can. I was certain I had already used one. And here it is. The Pepsi press-button can, it was only used during the '70s & '80s in Canada. The can was a failed design, since it required the operator to precariously puncture the opens using their fingers. Equaling loads of potential for slicing up your fingers at the expense of some sugary goodness. I'm guessing this can has a lot to do with my disinterest in offers of a soda.
Here's what Wikipedia on it:
One hole would be used for drinking the beverage and the other would act as a vent for air passage. Consumers could also easily cut themselves on the edges of the holes or get their fingers stuck.
Press button cans were used by Pepsi in Canada from the 1970s to 1980s and Coors in the 1970s. They have since been replaced with pull tabs.