It is hard to think of antonyms for the word "thankyous," as it is a term of gratitude and appreciation. However, there are some words that can be considered as opposites of "thankyous," such as ingratitude, disregard, and disrespect. Ingratitude means lacking appreciation and showing no gratitude towards someone who has done something good for you. Disregard means to ignore, disrespect or undervalue someone's effort, gifts, or kindness. Disrespect means to show a lack of respect towards someone or something. While "thankyous" express gratitude, these antonyms express the opposite sentiment of ungratefulness, indifference, and disrespect.