When Teresa observes other performers on stage, she’s thinking about how she can make her own performances better. There was a great deal of “borrowing” from other people’s routines among the vaudeville tours. This comedy sketch, perhaps one of the most famous of all time, was performed by Bud Abbott and Lou Costello from burlesque to vaudeville to radio to movies to television.
The following path, from the Abbott and Costello Wikipedia entry, gives an example of how that borrowing occurred.
“Who’s on First?” is descended from turn-of-the-century burlesque sketches that played on words and names. Examples are “The Baker Scene” (the shop is located on Watt Street) and “Who Dyed” (the owner is named “Who”).
In the 1930 movie Cracked Nuts, comedians Bert Wheeler and Robert Woolsey examine a map of a mythical kingdom with dialogue like this: “What is next to Which.” “What is the name of the town next to Which?” “Yes.”
In English music halls (England’s equivalent of vaudeville theatres), comedian Will Hay performed a routine in the early 1930s (and possibly earlier) as a schoolmaster interviewing a schoolboy named Howe who came from Ware but now lives in Wye.
By the early 1930s, a “Baseball Routine” had become a standard bit for burlesque comics across the United States. Abbott’s wife recalled him performing the routine with another comedian before teaming with Costello.