wouldn't shout if a shark bit him

a little bit of bread and no cheese

Used to represent the song of the yellowhammer (Emberiza citrinella).

bit by a barn mouse

tipsy; slightly drunk

butter wouldn't melt in someone's mouth

The identified person appears to be benign, mild-mannered, or calm (but with an integral suggestion that, to the contrary, they really are untrustworthy, disagreeable, or mean-spirited).

champ at the bit

To show impatience or frustration when delayed.

every bit

Exactly, to its full degree

give someone a shout

To contact or get in touch with someone.

jump the shark

Of television program or other narrative, to undergo a storyline development which heralds a fundamental and generally disappointing change in direction.

quite a bit

considerably