A cross joint is when you have 1 large joint and a shorter smaller joint and you join them through each other to form the shape of a cross. It is rumored that M.M. Oshonasy delveloped the first cross joint, the man who designed the golden gate bridge. What you do is you equip yourself with three lighters and you light all three ends at once which forms a trifecta of joint smoking power which helps you to get higher faster.
Man 1: Yo dude you gotta smoke this cross joint with me
Man 2: Na man i can't
Man 1: Come on man i can't even light this myself
Man 2: alright alright