I would imagine that going down to the mailbox, coffee in hand, opening the little door to find a used condom filled with helium would probably ruin my day. Any worse?
Letters from the IRS used to bother me, but now I guess severed body parts or pipe bombs would head the list.
Off to IMHO.
Cajun Man - SDMB Moderator
Thanks Cajun Man
I found a note, the other day, from my neigbours. Telling me they were going to repair their house and “it might be a bit noisy”
AAAAAAAAAAAAAAA
About 7 months ago, I would have said a big pile of anthrax, but I DID almost get bit by a black widow spider the other day getting the mail…scared the crap outta me! She must have been reading my Entertainment Weekly…maybe for Spiderman articles?
ummmmm, mebbe a letter from hubby’s ex??
Oh, no one here remembers the movie Se7en?
“Come on, what’s in the box?!” :eek:
Ranchoth
Bill Clinton
Or any other politician, come to think of it.
An AOL disk.
If a black widow bites you-will you die?
I would have to say a blood soaked rag. Or a needle with a note attached telling me I now have HIV.
A letter from the US Goverment that starts out,
Greetings
I once found a dead bird in mine. That was quite disturbing. Seems he had gotten in there and couldn’t get out. Not exactly the bills and whatnot I was expecting.
Real Life death threats from any of the plurality of people online who have threatened to kill me. 
That would be freaky.
A fetus.
a letter telling me my loved one is chosen as the leader of our very own right-wing LPF.
Tickets to a DeFranco Family Reunion Concert.
Ooooo good one. How about: tickets to a Celine Dion concert
The vast majority of letters sent to me by various government agencies have ruined my day.
“Dear Sir, the test results have come back and you have [whatever disease scares you the most].”
“Dear Sir, this letter is to inform you that you have been recalled to active duty . . .” I don’t know if they can really do that but it’s happened to people in a couple books I’ve read.
I saw a movie where a guy opened his mailbox and found a pissed off rattlesnake.
Daoloth’s fetus is pretty bad.
I suppose your dead pet or, worse, your dead child, or a part of one of your other loved ones would be pretty bad.
A black hole.