Think The Newlywed Game, but with siblings. That was the idea behind I'm Telling! The show started airing in 1987 and featured teams of siblings fielding questions about each other (and guessing how their partners would answer the same). The team that matched the most answers moved on to the Pick-a-Prize arcade, which I remember as basically a mountain of toys. One sibling would guess which of the toys he or she thought his or her partner would want; if the partner picked the same prizes, they won all the toys. Check it out.