The old joke goes like this (with possible variations in the reply):

Person A: Какой крепости чаю прикажете подать?
Person B: (Какой угодно, только не Петропавловской).

крепость has at least two meanings: 1) strength of tea, coffee, etc. , 2) fortress

Петропавловская крепость - used to be a famous prison in St.Petersburg (btw, this is the modern name of the city, Петроград was shortly used after 1917), at present it's a national historic site.

I guess the joke is clearer with negation (не).