from ireland.means to agree with something.its so true that you should chalk it down.
Paddy:Look at him,he's an awful tool.
Joe:Chalk it down
Means 'to make a record of something' or 'to have completed something noteworthy'. Usually shortened to 'chalk it'.
"I just got that girl's number. Chalk it."
"Chalk It Down" is generally used by stoners in Ireland, it can mean various things, too many to even list but people use it as a substitute for "chill" or "ok" or "in your face"
Girlfriend: Are you messing around with Lisa???!!!
Boyfriend: Whoah Chalk it down! (chill)
Boy1:You coming to the party tonight?
Boy2:Ya, i'll be there @ 9, chalk it down! (ok)
Boy:I fucked your 'ol doll
last night, ha chalk it down! (in your face)