Natalie's ex
It is driving me crazy. Who plays Natalie's boyfriend who dumped her via text??
shareWith all the cameos I passively assumed it was Ashton Kutcher. When you asked the question, I went back to check my assumption and can't say with 100% certainty as he's not credited at all. I did a little digging through the IMBD photo archive and it seems plausible.
Bottom line: it was either Kutcher or a look Doppelganger! :)
*edit*: Here's a link to somewhere near that time in Kutcher's life (they all grow up so fast! lol)
http://www.imdb.com/media/rm3889009664/nm0005110