I am going to let my son know that I picked him out from the garbage.
Why lie to your son about this?
I wanted to make a satire about a friend of mine who told me she picked a dog out of a rubbish. That's why.
It is strange to accuse people of pulling things out of the trash and try to make fun of them. Finding an abandoned animal in the trash is not worth of satire.
It is worth the rant. I mean half of the entire world is covered in trash.
It just does not make sense to lie about where the dog came from to your son. If your son finds out you are lying about something like this, it will be difficult for them to trust you on anything more important. Trust is very important for relationships in general.