Similar to Beer under the bridge:
When one or more stoned individuals either physically or verbally spars, and the next day they agree to forget about it since they were so high.
Nikki: "I bet Joe was mad about me yelling and hanging up on him last night when I was baked out of my mind."
Kristin: "He was toasted too. He said forget about it - it's bong water in the sink."
Prices shown in USD.