There are many ways to troll friends on minecraft.

Here are some of them

1.When they are sleeping, put COBWEBS around the bed!!!

2.When they are mining, dump lava into the hole they are digging in!!!

3.If they are in a house, make ditches around it and fill it with lava!!!!

4.If they are using anything (crafting table, furnace, dispenser) for a long time, just kill them.

5.When they are afk SURROUND THEM WITH COBWEBS!!!