Not know your arse from your elbow
idiom
To be completely confused or ignorant.
He doesn't know his arse from his elbow when it comes to computers.
Often appears as...
- doesn't know his arse from his elbow
- can't tell her arse from her elbow
Usage tips
Informal
Idiomatic
idiom
To be completely confused or ignorant.
He doesn't know his arse from his elbow when it comes to computers.
Often appears as...
- doesn't know his arse from his elbow
- can't tell her arse from her elbow
Usage tips
Informal
Idiomatic
Definition 1 of 1
Pro Tip 1/3Informal usage
This phrase is very informal and often considered rude or unprofessional.
In a casual conversation, someone might laugh and say, 'I don't know my arse from my elbow in the kitchen.'
Pro Tip 2/3UK expression
Predominantly used in the UK, this phrase may not be well understood elsewhere.
When I studied in the UK, I heard someone use 'doesn't know his arse from his elbow' and had to ask what it meant.
Pro Tip 3/3Emphasizing ignorance
The phrase is used to strongly emphasize a person's lack of knowledge in a specific area.
He tried to fix the car himself and ended up breaking it more—he clearly doesn't know his arse from his elbow.
Pro Tip 1/3Informal usage
This phrase is very informal and often considered rude or unprofessional.
In a casual conversation, someone might laugh and say, 'I don't know my arse from my elbow in the kitchen.'
Pro Tip 2/3UK expression
Predominantly used in the UK, this phrase may not be well understood elsewhere.
When I studied in the UK, I heard someone use 'doesn't know his arse from his elbow' and had to ask what it meant.
Pro Tip 3/3Emphasizing ignorance
The phrase is used to strongly emphasize a person's lack of knowledge in a specific area.
He tried to fix the car himself and ended up breaking it more—he clearly doesn't know his arse from his elbow.
Pro Tip 1/3Informal usage
This phrase is very informal and often considered rude or unprofessional.
In a casual conversation, someone might laugh and say, 'I don't know my arse from my elbow in the kitchen.'
Pro Tip 2/3UK expression
Predominantly used in the UK, this phrase may not be well understood elsewhere.
When I studied in the UK, I heard someone use 'doesn't know his arse from his elbow' and had to ask what it meant.
Pro Tip 3/3Emphasizing ignorance
The phrase is used to strongly emphasize a person's lack of knowledge in a specific area.
He tried to fix the car himself and ended up breaking it more—he clearly doesn't know his arse from his elbow.
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