An example of a useless product that can be purchased without any limitations is the "Pet Rock." The Pet Rock was a novelty item created in the 1970s by Gary Dahl. It was essentially a smooth rock, packaged in a small box with air holes and straw as if it were a pet, along with a tongue-in-cheek instruction manual on how to care for your new "pet."
Despite its complete lack of practical purpose, the Pet Rock became a brief cultural phenomenon, with millions of units sold during its peak popularity. People purchased it as a gag gift or simply as a whimsical conversation piece. It was a testament to the power of marketing and people's willingness to buy something amusing and utterly useless for the sake of novelty and humor.
Although the initial popularity of the Pet Rock waned, it remains a well-known example of a product that served no practical purpose yet was commercially successful due to its novelty value and clever marketing. Since there are no real limitations on purchasing such products, people can buy them for fun or as collector's items, even though they serve no functional purpose in everyday life.