Once Link gains the ability to merge with the wall, there are several easter eggs and silly things you can merge into. First and obviously, Link can merge into the wall in his house and slide behind Majora's Mask, making it seem as if he is wearing the mask.

Several houses in Kakariko Village have portraits and paintings in their houses that Link can merge behind. Slip behind a portrait of Makar's mask from Wind Waker, or a Cucco head, or even a Skull kid head in Thieves' Town!

The Stylish Woman in Kakariko blows Link a kiss every time he enters the house, but she's also gotten lipstick on the right wall. Merge along the wall to give Link lipstick on his face!

When entering Hyrule Castle with the Master Sword, Link can merge along the paintings retelling the events of Link to the Past. You can even take the place of the place of the Link in the painting!

Link's appearance while wall merging also changes depending on the tunic he has equipped, if he is holding a lantern, and even the border that forms as he merges changes color depending on his tunic.