Sleepy Boo

Sleepy Boos, also known as Giant Boos or Big Boos , are medium-sized Boos that appear in Super Mario Sunshine. During Episode 3 of Sirena Beach, Mysterious Hotel Delfino, Mario encounters them in Hotel Delfino.

Description
Sleepy Boos are stationed in various passages; most of the Sleepy Boos appear in the hotel's attic, and one is also located on the second floor of the hotel, blocking the sole passage between two rooms. There is no room to pass or jump over them, and F.L.U.D.D. has no effect. Though they do not wake up in response to anything, they will do one point of damage to Mario if he makes contact. The only way to defeat a Sleepy Boo and clear the way is for Yoshi to eat it.

If Mario is riding on Yoshi's back and runs into a Sleepy Boo, he will take be flung off the Yoshi as usual; however, it is very hard for Mario to mount the Yoshi again afterward, as he will still be too close to the Sleepy Boo and Mario will very likely be knocked off again.