Take one's chance as to what meal one is served when accepting another's hospitality.
Potluck is also used in the USA as the name of a communal meal, in which participants each bring a dish to be shared. A reference to potluck is made in the New York Times, in August 1867:
"Simple mechanics, thinking of nought beyond their wages, their pot-luck and their ponies."
The context of that citation isn't entirely unambiguous, but the entry in American Speech in 1924 is quite explicit:
"Pot luck, food contributed by the guest. To take pot luck is to bring food with one to a party."
The US usage is long pre-dated by the original UK usage and the 'take one's chance at what is being served' meaning is still the one that's is understood there. Thomas Nashe recorded the term as early as the 16th century, in Strange newes, of the intercepting certaine letters, and a convoy of verses, 1592:
"That, that pure sanguine complexion of yours may neuer be famisht with potte-lucke."