Texture trolling :
1 Change the lava texture to water
2 Change all the ores ti stone
3 Make all the mobs invisible (erase the skin)
4 Change door texture to the block that his/her house is made of so he/she cant find the entrance

Sound trolling
1 Change door sound to creeper blowing up
2 Change preasure plate sound to TNT (or creeper if you want to change the door to TNT)
3 Change the block breaking sound to enderman/dying enderman

"sabotage" trolling
This kind of trolling is a little bit difirent because you have to get acces to your friends computer go to his/her house/hack etc.

1 Get acces to computer
2 Take a picture of something scary in minecraft (Herobrine/Enderman etc.)
3 Make that his/her wallpaper
4 Enjoy :3