The line comes from Ace Ventura: Pet Detective, the 1994 comedy starring Jim Carrey as the eccentric animal detective. 'Alrighty then' became one of Carrey's signature catchphrases, repeated throughout the film whenever Ace accepted a case or brushed off disbelief with cheerful confidence. As clips circulated on soundboards, social video and meme edits, the short phrase took on a life beyond the movie, becoming shorthand for enthusiastic agreement before something silly happens. It remains popular because the delivery is instantly recognisable, even to viewers who have not seen the film.