First thing you know he'll hoist the Jolly Roger, and then there'll be some queer doings in these waters." "Hoist the Jolly Roger ?" "I mean turn pirate, so to speak.

You keep your eye on that boy, Lucy.

Something's going to break loose or I'm a Dutchman." Bob's father thought his son's subdued behavior on the few days following the captain's arrival was due to a hint Bob had obtained, that, unless he mended his ways, he might be sent on a long voyage to work his passage.
Now the truth was that Bob was merely waiting for a good chance to play a trick.

He was not particular what sort of a trick it was so long as it created a laugh.

The consequences never gave him a thought or worry.
So, as he could think of nothing sufficiently "funny" to do, he remained quiet.