Alright buddy, have you ever seen an ad on TV for something that you couldn't buy? Like a fancy alcohol called "Royal Stag" or a cigarette called "Marlboro"? That's called surrogate advertising! It's basically when companies advertise one product (like glasses or watches) but they really want you to remember their brand name (like "Royal Stag" or "Marlboro").
This is because some countries have laws that ban ads for products like alcohol or tobacco, because they can be bad for your health. But companies still want people to know about their brand, so they come up with creative ways to advertise it without actually showing the product. So when you watch an ad for sunglasses, but hear the brand name "Royal Stag" a lot, the company hopes that you will remember that name and want to buy their product if you ever see it in a store.
So basically, surrogate advertising is a sneaky way for companies to promote their brand and make it memorable, even if they can't show or talk about their actual product in an ad. Isn't that kind of interesting?