It is commonly used in malayalam, to refer to some joke which is of an obvious sort and does not make the listener laugh. In short, it is used to describe a failed joke or a joke that lacks humorous elements.
"That joke he said is a chalu! It's not funny at all."
"He tried to impress her with a joke but it was a chalu!"
"He tried to impress her with a joke but it was a chalu!"
by languagelover2004 April 09, 2018