Robbie Douglas' (Don Grady) nightmare is about joining the French Foreign Legion. This organization was founded in 1831 and is a unit of the French Army. It is open to foreign nationals, who serve under French officers.
When the two older brothers start talking about striking, Chip mistakenly thinks they are talking about baseball. Mike confuses him even more by saying they'll have to at least get to first base if they are going to get anywhere with Steve. Chip then asks how can they get to first if they strike out. There is in fact a rule in baseball, that if the batter strikes out but the catcher drops the ball, the batter can run to first hoping to beat the throw. It rarely succeeds, but some batters do make it safely to first. Strangely enough, the strikeout still counts, which explains why there are a tiny handful of pitchers who have managed to get four strikeouts in one inning.