When a woman accidentally lactates a small amount of milk on her shirt. This can be due to overexcitement, it can be random. The resulting stain is known as a Boob Spot. Boob Spots are hilarious, especially to any observing friends, and should not go uncommented on.
"Dude what is that weird discoloration on Megan's shirt?"
"That, my friend, is a boob spot, she got a little too excited when she saw Travis..."