Hello so basically this lanked 6ft 4 kid challenged me to a arm wrestle and im 5ft 9 and go to the gym often doing biceps and stuff like bench.How do I arm wrestle him.if I lose which is possible I'll lose all my reputation and be mocked alot.i need tactics that work.He has also got good stamina but I got muscle.

I don't really Height mattering here. In fact shorter people I believe are generally stronger.

Its the arm size and strength that matters most and not height.

Go 100% and try and overwhelm him.

Correction he is lanky

give them a hand job under the table