"Stoned" usually means high on pot (marijuana). But back in the first half of the 20th century, people would sometimes use "stoned" to mean "drunk." So it depends on when your source is from. If it's 1970s or later, it's almost certainly talking about pot.
To clarify, the other kind of "stoning" that we're joking about is executing a person by tying them up or otherwise immobilizing them, and then throwing stones at them until they die. So you could also say that someone who was executed that way was "stoned." But you wouldn't say they were "too stoned."