Frog in his pocket 

When someone uses the pronoun "we," but no one else actually wants to be included. Implies that the speaker must be referring to himself and the frog. Typically takes the form of the rhetorical question, "is there a frog in your pocket?"

Alternatively may be a mouse or other pocket-sized creature.

Billy said "we're going to clean up the apartment today," but it's all his mess. He must have a frog in his pocket.

Boyfriend: I've decided that we're going to go vegan.
Girlfriend: You got a frog in your pocket?

Frog in his pocket by monocledmoose January 24, 2022

Frog In His Pocket 

Interchangeable with 'stick up his ass'. Figurative statement meaning irritable or stuck up.

Dude did have you talked to John today? Has he got a frog in his pocket or what?

Frog In His Pocket by Paulsac September 30, 2007

Frog In His Pocket 

Somebody of less than normal or childlike intelligence. Derived from the idea that a dim witted child might collect and keep in their pocket objects of interest, such as a bottle top, a piece of string ,marbles and a frog.

" I am not sure about that guy up the street. He seems like he's got a frog in his pocket!"

Frog In His Pocket by patto98 December 17, 2016