Letter to the Postman: Step 2 - Use Duct Tape to Seal It!

So, you've labeled the envelope properly, congratulations! Now it's time to seal it up with some good ol' duct tape. Don't bother with those fancy-schmancy envelopes with adhesive strips, no, no, no! We're talking industrial-strength, neon-yellow duct tape here. Wrap it around that envelope like you're trying to straitjacket a greased-up pig. Make sure to get that tape nice and tight, no air pockets, no wrinkles. You know, for security reasons.