Press Ctrl + W and check "by Pixels"
Set the values to 561 Height and 561 Width
Ctrl + S to Save it.
Step 4.now just save the image into your device on the path ?/sdcard/WhatsApp/Profile Pictures?.Step 5.Turn of Wifi or Deactivate data network for a while.(till you prank your friend). as his real profile picture will not Download then
Step 6:Show and Appreciate him for his new profile picture by showing him
and he is trolled.There are other small hacks also such as free whatsapp for over a year or hide last online time if you want them then visit