This weekend I have a family 'picnic' [=a picnic with family members] to go to.
Breaking a leg is no 'picnic'. [=breaking a leg is not a pleasant experience]
Being president isn't exactly a 'picnic'. [=being president is not easy]
(..) Did you hear that building? It was moaning. It's just the wind. Oh, what a beautiful place. We should have brought our lunch. Then we could have had a picnic. Look. They were planning to put a river here. Hey, you smell that? - Something smells delicious. - Yeah, and I'm starving. (..)2001 Spirited Away