"There's a trap door in the garden! I almost fell down it!" He might think he's imagining the trace of amusement in their voice. Frisk's embraced their weird track record of falling places, or almost falling places. At least they avoided it that time.

They look down. "Just 'f you do!" Cold and wet isn't something they mind; they want to see if there's something at the bottom of the castle, too, if they can.