[greenslime (OP)]

Well not entirely where do the bubbles come from but if you have a pint of beer at a pub or whatever drink you drink, a fizzy drink, when you look at the bubbles that appear from the glass they just appear out of nowhere from fixed positions. Why does this happen? Why do they not come from random places all the time?

[Make it Lady]

The bubbles of gas are formed on minute defects in the glass. Bubbles tend to form more rapidly on rough or wrinkled surfaces hence it would be cruel to put your granny in a bath of cola. Other experiments that demonstrate this are putting salt or sugar into your fizzy drink. The bubbles form so quickly on the introduced crystal surfaces that your drink will fizz up and overflow. For extreme experimenting put mentos into large cola bottle. Topically volcanos have the same problem. changes in pressure due to plate shifts will cause the rapid formation of gases that will errupt explosively. 

[Make it Lady]

Watch this for a lark