Miss You Card
Taken either as a threat or a thoughtful gesture depending on the intelligence and location of the recipient, this clever card is perfect for so many occasions. An ex-wife for instance could send this to her ex-husband on their anniversary. That's all I can think of for now. I'll take suggestions in the comments.
Watermelons. You poor bastards. Always on the receiving end of novelty weapon violence. The Gotcha Cap. The Unbreakable Slugger Umbrella. The <a href="http://www.dudeiwantthat.com/gear/weapons/blade-driver-crossbow.asp"
If you like Exploding Kittens - you sadist, you - you'll probably also like the party game's 3rd expansion pack, Barking Kittens. Though by the title, it sounds like the 20 new cards included in this release are more...