There is no such standard of “proper” usage. A kid in a sitcom can say “I don’t want Legos for my birthday” or “I don’t want Lego blocks for my birthday.” The trademark owner might prefer the latter, but has no recourse (other than to send stern letters) if the line said is the former.
Bottom line: We, as citizens, as writers, as broadcasters, as movie producers – basically as any kind of speaker – can use a brand name however we want. Trademark owners have absolutely no right or power to control our usage of language. It’s only when we slap that name on a product or service we’re selling that we can get into trouble.