I like this definition at urbandictionary:
Contrary to popular belief a Lid is not an ounce of weed. The coffee cans had a key like a sardine can and the Lid would be wound off the can. The Lid used to measure usually contained about 4 fingers of pot. People at that time didn't have a triple scale to weight pot.
"And though we'd eliminated the threat of the enemy flying planes into buildings, no-one was prepared for terrorists flying two buildings into the sides of planes. No-one was killed but a lot of people were surprised." -Time Trumpet, Episode 3