ShempisAwesome, I modestly believe I have answered your question as to whether the lyric " Curly's A Dope " is an ad lib by pointing out, quite a few posts north of here, that it is in perfect harmony and obviously pre-recorded. It couldn't possibly be an ad lib. It is certainly meant to sound like one, though, and Curly's reaction to it is certainly meant to get a laugh because of that perception, but a careful viewing will reveal the techniques that went into that sequence, none of
which are ad libbed, since everyone in this entire sequence is lip-synching .
Remember that Charley Chase, the director of this film, was one of the greatest comedy directors, and his films, including these few stooge films that he directed, were full not only of big belly-laughs, but also little tiny bits like " Curly's a Dope ".