On each stair they were told a joke, and they got funnier every stair higher.
The first brunette only made it to the first stair.
The second brunette made it to the fifth stair before she laughed.
The blonde slowly made her way up all the stairs, until finally she was at the 99th stair, where she let out a chuckle.
The brunettes, in awe of how well she did, asked her why she laughed.
She replied “I finally got the first joke”