Duff beer from the Simpson's is something that's been made and can be bought in real life, though it isn't a beer, it's an energy drink. I like how the imagery has been kept so true to that of the cartoon. It's pretty recognizable.
For all those who watched Lost they will recognize this. The design of everything on the island has been stripped right back to the basics in black and white with the logo and saying exactly what it is. It has no frills.
Romulan Ale is an alcoholic drink from the Star Trek universe. It looks like it could glow in the dark which is a quality that I reckon PGGB could have.