Responses
Really wild guess.. It's not lunch box., but tools box..
http://www.mangago.me/read-manga/ore_no_shita_de_agake/mf/v01/c002/
This is nothing like your description but does involve food and throwing stuff lol
http://www.mangago.me/read-manga/koi_no_shizuku/an/koi-no-shizuku-chapter-3.html
guya drops a lunch box on guyb's car from a from a high place and guyb turns out to be turns out to be guya boss or something like that I can't really remember (≧∀≦)