Lactating Cow
A cow who can't help but leak milk everywhere, like a person who can't stop talking over everyone else in a conversation.
My uncle is like a lactating cow at Thanksgiving. He talks over everyone and no one can get a word in.
She started lactating in the middle of my speech. I was like, 'Are you even listening?'
He walked into the room and started lactating. It was like a milk fountain.