The pope's mustard maker noun phrase informal
A conceited person, especially one in an insignificant job or role
Bin is just a cleaner but he acts as if he is the pope's mustard maker.
She seems to be thinking of herself as the pope's mustard maker.
Acting and behaving like you are of great importance, but actually, you aren't
Conceited or overly proud
Used to refer to a sarcastic person
If something is beneath someone’s dignity, they feel that they are too important to do it.
Used to describe someone who is extremely vain or conceited
Pope John XXII had a personal "moutardier" (mustard-maker) to ensure that his food was correctly seasoned in the 14th century.
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.