“Takayama-san proved in today’s meeting that he is completely out to lunch.”
Lunch on
To be invited to lunch because one can amuse or entertain the host
“Fukuda-san will lunch on his friendship with the Prime Minister for many years.”
Eat (them) for lunch
To devour the competition, to thoroughly beat them
“We’re not afraid of our competitor’s product introduction next week. We’re going to eat them for lunch.”
There’s no such thing as a free lunch.
A famous saying: nothing in life comes without a cost
“My boss offered to let me use his ski condominium but now he wants me to work next weekend without pay; I guess there is no such thing as a free lunch.”
Liquid lunch
Drinking alcohol instead of eating food
“It was clear that the entire sales team had a liquid lunch; they all fell asleep in the afternoon meeting.”