A burr under (one's) saddle phrase
Used to refer to a source that causes persistent annoyance or irritation
The noise from the construction work next door has been a burr under my saddle for months.
The continually disrespectful attitude of students toward teachers has long been a burr under his saddle.
I don't mean to be a burr under your saddle, but can you lend me your car this only last time?
Used to say that you would like to do something, typically because of annoyance or irritation
Someone or something annoying
Used to ask why someone is irritated or in a bad mood
The origin of this phrase is not clear.