Not only must you keep the characters themselves pure of any violation of their unity, but you must also see to it that every big laugh is given to the comedian. If the comedian is the one "getting the worst of it"—as is almost invariably the case—he must get the worst of it nearly every time. But that does not influence the fact that he also gets almost all the laugh lines.
Note the working out of the laugh lines in "The Art of Flirtation." You will see that only on the rarest of occasions does the straight-man have a funny line given him.
The only time the feeder may be given a laugh line, is when the laugh is what is called a "flash-back." For example, take the point in "The Art of Flirtation" beginning:
COMEDIAN
And does she answer?
STRAIGHT
She's got to; it says it in the book.
COMEDIAN
Does she answer you with a handkerchief?