Referring to the period after which a drug ceases to have it's effects felt. A Come-down. Conversely, the initial effects would have the user experiencing a dope-smile, but uttering such a antithesis would be in essence dopey, and/or idiotic.
Dude! I had such a "dope-frown" an hour after I smoked all that weed, I had to drink another couple of beers to get back up there again.