Pictured: what 20-somethings say when they want a burger.
For a blip of time in the mid-2000s, an animated banner ad with those three frames proliferated around the Internet. It even came out that the advertisers had no clue that "I'd hit it" had any sexual innuendo associated with it at all - they sincerely thought that it was like any other throwaway slang from the younger generation. By the time McDonalds could redact the banner ads, it had already been mocked to hell and back.
This gaffe is best explained by assuming the advertisers were out of touch with their audience. In a lot of ways, this is a problem with online advertisement in general - they're out of touch with their audience, and everyone suffers for it.
