Smeech

Smeeches are pig-like enemies first appearing in the game Super Mario Galaxy 2. They appear as pink winged creatures with two beady eyes and plump lips.

Super Mario Galaxy 2
Debuting in Super Mario Galaxy 2, Smeeches' only method of attack is kissing and sucking Yoshi's lips, making him unable to use his tongue or eat fruits. If Yoshi tries to eat one, the creature will suck on his lips. They can only be defeated with a Spin or get jumped on. Also, they will flee from Mario or Luigi if they are not riding Yoshi. To get a Smeech off Yoshi's mouth, Yoshi himself has to spin his head to make the Smeech vanish, dropping Star Bits. If Mario or Luigi dismount or get knocked off Yoshi, the Smeech will detach from Yoshi's mouth and hover away.

Smeeches are first encountered in the Yoshi Star Galaxy, ever since the first mission, Saddle Up with Yoshi. They are encountered later on in the Hightail Falls Galaxy, the Haunty Halls Galaxy, the Sweet Mystery Galaxy, and the Starshine Beach Galaxy.

Trivia

 * Smeech is a portmanteau of the words "smooch" and "leech".
 * They bear a striking resemblance to the Poink enemies from Bianco Hills in Super Mario Sunshine, in both their appearance and their method of attack, as these creatures would attach themselves to F.L.U.D.D.'s nozzle in the same way as Smeeches attached themselves to Yoshi's mouth.
 * Smeeches also bear a faint resemblance to Love Bubbles from Mario and Luigi: Partners in Time.
 * If Yoshi goes up to a Smeech and another one is already on his lips, the Smeech won't take any notice of him and keep hovering around like normal, making an easy target to be stomped on.
 * If Yoshi collects a Power Star with a Smeech on his lips, it will appear in the "You got a star!" scene, still stuck to his lips.
 * A Smeech will also stay on Yoshi's lips if he takes a Launch Star.