There was a big conference of all the beer producers in the world. 

After a hard day's work they decided to go out and have a beer
together. The president of budweiser got a bud, the president of
Heineken gets a heineken, the president of miller gets a miller
lite, the president of coors gets a coors, etc. The waitress
asks the president of guiness what he wants and to everyone's
surprise he orders  a coke. "Why don't you have a guiness?", his
colleauges asked. "NAAH, if you guys won't drink beer then
neither will I.