A Candian friend said this to me today:
so, if you know any schools looking for a physics teacher, I'm down.
What does "I'm down" mean here? Apparently it doesn't mean "I am upset".
An English teacher told me that it means "I will join in".
Could anyone explain it and tell me which entry (a link is much appreicated) in dictionary fit this meaning? Because I tried Oxford dictionary, Collions and Merriam Webster, I couldn't find related entry. Thanks