Exclu-stiff

The new season of "Workaholics" is already facing hard times ... and it hasn't even aired yet.

The good people over at Comedy Central just put the above billboard up on Sunset Boulevard in Hollywood -- and if it wasn't glaringly obvious ... it features a trio of six-foot boners pressing against some kind of elastic fabric (spandex?).

For those who haven't watched yet, "Workaholics" is about three recent college grads desperately trying to adjust to adulthood.

But by the looks of the billboard -- they'll be fully grown in Season 3.