It is most definately "cheerily" but it is pronounced "cheer'ly", and that is where the confusion stems from.
"Screw him up" is an expression used aboard sailing vessels and means tighten up. It probably comes from the use of Jack Screws, which were employed to stow cargo as tightly as possible below decks - usually cotton bales, but other bulky stuff as well.
Dancing Master is correct, the switch to Boarding Master is most amusing, and speaks more about folk clubs wanting to do "the right thing" and so completely missing the point.