"Y'all'd" is a contraction commonly used in some Southern American English dialects. It combines "y'all," which is a contraction of "you all," with "would," creating a form that expresses a conditional or hypothetical situation involving a group of people. For example, "If y'all'd come to the party, it would have been more fun." This contraction reflects the informal and conversational nature of Southern speech. While it may not be widely recognized in formal writing, it captures the regional flavor of language and is often used in everyday conversations among friends and family in the Southern United States.