Muddy water or just getting drunk?

[gbauws]

What is the origin of "Here's mud in your eye"

[geofbob]

This informal toast is supposed to have originated in the First World War trenches. If a shell landed near a soldier, he would be very fortunate if he merely got mud in his eye, rather than being maimed or killed. So "Here's mud in your eye" became an ironic way of saying "All the best".