A portmanteau of the words squee and emo (or screamo). Essentially means the indie/emo/pop-punk scene of bands whose main selling point appears to be that they can make girls squee. Generally found/famous through Myspace and Purevolume
Their fans can typically be heard saying "But they're so cute! This song just makes me squee!"
"Oh wow, you're into *Band Name Here*? Ehh, I don't like them that much, they're kinda squeemo."