Jimmy Fallon and Russell Crowe celebrated Earth Day last night by singing about that times humans were really, really bad to their mother. This week also marks the fifth anniversary of the BP oil spill, so Fallon started playing his protest song, "Balls in Your Mouth." Crowe, a fan, thought it was so on point he told Fallon BP should "come here and get on their knees right in front of you." No longer able to resist the song's pull, Crowe pulls out a strategically placed guitar and joins in on the double-entendre ditty. 

Watch their performance above.