The Internet is the destroyer of innocence. (You heard it here first, folks.) Destroyer of Innocence.
My husband was raised as a NO TV, ultra-conservative, hardcore homeschooler. (I was homeschooled, too, but we watched Star Trek, MacGyver, and the A-Team, so I'm slightly less sheltered.)
After we'd been married for about a year, my innocent husband played this innocent game online and he learned – dare I say it? – the Your Mom joke. I remember the day it happened.
Player 1: “Ur a n00b.”
Player 2: “That's not what your mom said last night.”
And that was it. From then on Your Mom was included in every dinner conversation. Shortly thereafter it progressed and my dear, sweet, wholesome husband became captain of the That's What She Said team.
(It must be said that I am not a complete bystander in this. I enjoy participating in the Your Mom jokes and am very quick to instruct my husband regarding when Your Sister is much more effective than Your Mom.)
Last night, after several rounds of Your Mom's, we reached this point at the dinner table:
Me: “That's not what your mom said last night.” (we laugh) “You know, I never realized your mom was such a whore.”
My Mister: “A what?”
Me: “A whore. W-h-o-r-e. One who makes sex for money.”
My Mister: “Oh, well at least she makes some money with it. Your mom does it for free.”
See what I'm talking about? Innocence destroyed! So, guard your children.
Of course the “Your Mom” in these conversations is always hypothetical since actually suggesting such things about your Mother-In-Law doesn't lead to marital longevity.