A phrase that can be used for many things
1. To shout "BANG" while moving
2. To have have sexual intercourse in something moving
Dave: "Hey Reece, shout bang into that phone box."
Reece: "Ok, BANG!!!"
Dave: "Wow that was such a mobile bang"
Bob: "Hey Mum, lets have sex in that mobile home."
Mum: "OK, let's get started immediately"
Bob: "Wow we just had a mobile bang"