* Formal: The debate about the merits of free trade could continue ad infinitum, with no clear resolution in sight.
* Casual: My cat could stare at a laser pointer ad infinitum if I let her.
* Figurative: The company's marketing campaign was based on repeating the same slogan ad infinitum, hoping that sheer repetition would make it memorable.
* Humorous: I could tell you stories about my childhood ad infinitum, but I think I'll spare you the details.
Note: "Ad infinitum" is a Latin phrase meaning "to infinity" or "forever." It is often used to describe something that continues without end or limit. It's more common in formal writing and speech.