Knock Yourself Out
‘Knock Out’ is a boxing expression. It means to hit someone so hard that they cannot get up (in 10 seconds). ‘Knock Yourself Out’ is very different. It does *not* mean ‘Hit yourself!’ It means ‘Go ahead. Do whatever you want.’ For example, if my friend says ‘Can I have one of your chocolates?’, I will say ‘Knock yourself out!’ This means she is welcome to eat lots of my chocolates. This expression is usually friendly, but if someone doesn’t smile and uses a flat tone, it can be negative (or joking). In that case, the nuance of ‘Knock yourself out’ can become ‘I don’t care (what you do)’.
A: I’m going to the toilet.
B: Knock yourself out.
Talking Point(s): Do you think ‘B’ in the example above is using ‘Knock Yourself Out’ to mean ‘Go ahead!’ or ‘I don’t care’?