<human>: This happened on Halloween two or three years ago.  

I was at the door handing out candy while my wife took the kids trick-or-treating. Sometimes the kids really don't bother with costumes, but other times whole families really get into it.  That was definitely the case with one Star Wars family.  Mom looked awesome as Princess Leia, dad was properly suited up as a decently menacing Darth Vader, and their four-ish year old son was a credible Luke, complete with the mop of dirty blonde hair.  Adorable.

I always like to say something to the kids, especially if they've made an effort, rather than just tossing the fun size Snickers into their bags, so I crouch down to the kid and start talking.  "Is that your lightsaber?"  "Can you use the Force?"  And then to kid around a bit, I point at dad and try to crack a joke about the whole "Luke, I AM YOUR FATHER" line.  

But what ends up tumbling out of my mouth to the kid is "You know, I don't really think he's your father."  Jaws drop, silence ensues, as the kid sits there speechless as it sinks in that I had really botched the movie reference and the whole family actually just heard me tell the kid that Daddy isn't really Daddy.

After an uncomfortably long moment they quickly turned and stepped off the porch into the night while I slunk back inside.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Meant to make a Star Wars joke reference, ended up telling a four year old he was a fatherless bastard.