there are a lot of things you can do in Minecraft to hide bases or even trap your friend. I am going to tell you some of them . if you want to troll your friend you have to be very sneaky about it . to make a secret base you have to make it somewhere or make something you have to do to get in that know body would think of .1. make a moat of lava with a bridge over it and hook some pistons and drop.
2. put your base underwater and put only Redstone torches so it does not put off to mush life .
3. put a anvil above a door and drop it on there heads .
4. make a house in lava and put signs then take a leap of faith .
5. put some gravel so when they walk over it they fall .
