This Munchkin t-shirt is themed for Munchkin Apocalypse. It is a spoof of the four horsemen of the apocalypse, instead showing four horsies in the style of My Little Pony.

The shirt-specific Munchkin rules (items #2 and #3 from the main board game description) are as follows:

2) If you are wearing this shirt when you kill the Four Horsies of the Apocalypse (from Munchkin Apocalypse), either as the main combatant or as the helper, draw an extra Treasure. 3) The signatures of Steve Jackson, Andrew Hackard, or John Kovalic on the shirt each give you another extra Treasure, to a maximum of four at once. Note: Defeating the Four Horsies in some nonlethal fashion does not give extra Treasure. If you are the helper, the main fighter draws the Treasure face-up - but the extra goes to you.