Theories abound. Confusion abounds even more.
"My cat does this all the time. If I don't let her in with me, she puts her paw under the door until she finds my foot to hold onto," onereddit commenter wrote. "Sometimes I'll put my hand down and we'll hold 'hands' through the door, she purrs like mad when we do this."
"This is painfully cute," another commenter replied.
"Cats have that toddler mentality," another wrote. "If you're doing anything behind closed doors it means you're having fun without them. They want in on it."