Put a fart balloon or fart pillow under the cusion of the seat of a lounge suite when you know important visitors are coming over. We did this to our Pastor when he did a house call. The first two times he visited us he used the same seat so we were pretty sure he would take up the same seat on his next visit. This is the perfect harmless prank for creatures of HABIT.
This prank is good for when you're at home or at someone else's house! Grab the victims tube of toothpaste and squeeze the rest of the toothpaste out. Then grab eg tomato sause, BBQ sause, mustard or sweet chilli and squeeze just the right amount of it then wait until the morning and watch them brush their teeth with dinner!!!
If the toothpaste is white you can replace it with thick creamy mayonnaise to make it less obvious.
For a completely "disguised" toothpaste prank, take some of the pips of a chilli (this is the part of the chilli that causes the BURN!). Without squeezing any of the toothpaste out, carefully work the pips into the tube of toothpaste with a food pick. Wait for the BIG BURN and the reaction to the unexpected coarseness!
Ask gran to lie down for a pamper session. Put a towel on her face. Say you are putting face cream on her. Really do it. Next, tell her to keep the towel on for a few minutes. Then say you are going to give her spray on nail polish. Keep the towel on her! Spray oil on her feet for the nail polish. Spray oil on her hair as hair spray! You can even put honey or powdered sugar on her! Then finally, take the towel off her face! If she is a fun gran she will find it funny. It is hilarious!