like there is the question mark and exclamation point at the end of a sentence. How you show that a statement was meant as sarcasm or showing irony is unclear. There actually is !? to show sarcasm but most people don't know it, so they think your asking a question.
How about ,S at the end of the sentence, for sarcasm and ,I for Irony?
?
Irony punctuation is any proposed form of notation used to denote irony or sarcasm in text. Written English lacks a standard way to mark irony, and several forms of punctuation have been proposed. Among the oldest and most frequently attested is the percontation point proposed by English printer Henry Denham in the 1580s, and the irony mark, used by Marcellin Jobard and French poet Alcanter de Brahm during the 19th century. Both marks take the form of a reversed question mark, "⸮".
Irony punctuation is primarily used to indicate that a sentence should be understood at a second level. A bracketed exclamation point or question mark as well as scare quotes are also sometimes used to express irony or sarcasm.