The Big Dictionary of Dreams
by Martha ClarkeDreaming of a skull also refers to mortality and to your spiritual contemplation about the beginning and the end of life. It can also express things that are coming to an end or whatever you are just unable not reach.
For gypsy people, skulls are the wisdom of their ancestors. Drinking from one of those means sharing this old knowledge. In Ireland it symbolizes the truth because it is said that if an individual takes false oath with a skull, she will die soon.
Dreamers Dictionary
by GarudaVision: Seeing a skull: a reminder to be honest and to look at reality with a sober mind.
If you can do that, you are going to succeed. Digging somewhere and finding a skull: you will receive a monetary gift.
Depth Psychology: See Head, Skeleton.