Sounds pretty mean. Even though I have the tendency to be mean, I'm talking about making someone cry WITHOUT them knowing. *SHH*
Using Photoshop you can make someone you love (or hate) shed some tears. Obviously this won't be as realistic as the real thing but at least you don't end up looking like a jerk.

So basically turn this into . Hey, just because I eternally love TAI and William Beckett doesn't mean I can't make him cry. Plus it was fun. Eeek.

     Do the usual stuff : crop, resize, sharpen, etc. Center cropping will not work if you want to add ANY text.

 Desaturate and increase the contrast using selective color, brightness/contrast, whatever works.

  Now for the fun stuff:  On a new layer, use a blood brush or tear brush of any kind, as long as it fits and has a running-tear shape.  Blur the bottom of it to make it look a bit more realistic.

   Set the teardrop layer to screen. Don't worry, it'll show up soon. Go to Layer Style, click on Bevel and Emboss: Inner Bevel, Depth between 50% and 100% (always depends on image) and  size to 5.

  There you have it! I added some text, do with it what you like. The great thing about this tut is you could possibly make yourself happy by making an enemy cry without a possibly bad result. Ah, the magic of Photoshop CS.