This phrase is used after somebody has just ripped another person and it is too harsh to laugh. So to break the tension and to try to diffuse the situation, a third person says in a deep Nigerian accent " THE BANTER IS FLOWING" and then everyone can then laugh without feeling harsh.
Will: Your a cock Dylan! No wonder your mum made me wear a condom when I fucked her, she doesn't want another fucking accident like you!
**awkward silence**
Danny: "THE BANTER IS FLOWING"
**everybody laughs**
banter rip ripped awkward silence