Actually this is pretty easy. First of all you got to get a stack of exactly 1 TNT and place it down where you want it to explode. Be careful not to put anything else in the slot the TNT was in because that’s now shadow-linked with the TNT you placed. You need to somehow get a redstone signal to activate in the same tick as you punch the TNT block. It’ll take a bunch of tries. Be careful not to pick up the dropped TNT item, or it’ll go into the shadowed slot. That part is pretty random. Next open up the chat and type “BOOOM!” or similar. It helps if you copied the text beforehand so you only have to paste it in. Log out of the server and never come back because you’re a bad person.

Oh go away, nobody likes griefers.

For what purpose? To be an asshole?

TNT is server side, so no not really.

TNT isn’t the sole way to grief. Try lavacasting/lavawalling the target area.