I remember the scene in the TV show "How I met your mother" where one of the main characters, Marshall, goes to visit his dad's grave with a BBQ and some beers to watch a game(of football?) with his dad like they always used to. I thought it was extremely unusual but actually, kind of lovely.

Where I come from(Poland) cemetaries are almost sacred, instead of halloween we celebrate "wszystkich świętych"(all saints day) where everyone does the annual pilgrimage to the graves of their families to pay their respects. At the end of the night every cemetery is glowing with candles, all graves are adorned with flowers and other decorations it's all very solemn and sirious - I think the idea of a "picnic" at a cemetery would be seen as very disrespectful here - but it's still very interesting.