marty was called out in something called the water bucket challenge. when this happens you have 24 hours to either have a bucket of ice water dumped on you or pay $100 (i think).

when marty told the kids about it, they each had a different reaction.

BELLA
oh! who are you going to challenge next. you can call out three people.

ALEX
do you have a hundred dollars to pay them? you should pay them.

ANTHONY
can i do it? ("it" being have water poured on him)

marty then added that that pretty cleanly summarized the personalities of her three children.