Hartford, Conn. ? Passing notes in study hall or getting your best friend to ask a boy if he likes you or, you know, LIKES you, is so last century. Nowadays, teenagers are snapping naked pictures of themselves on their cell phones and sending them to their boyfriends and girlfriends.

Many of these pictures are falling into the wrong hands – or worse, everyone’s hands, via the Internet – and leading to criminal charges.

Some parents are aghast.

“I just don’t understand why kids would do a stupid thing like that,” said Rochelle Hoins of Castle Rock, Colo., where 18 students in her twin sons’ middle school sent around nude pictures of themselves last year.

Similar cases have been reported in New Jersey, New York, Alabama, Utah, Pennsylvania, Texas and Connecticut.

School administrators in Santa Fe, Texas, confiscated dozens of cell phones from students in May after nude photos of two junior high girls began circulating. The girls had sent the photos to their boyfriends, who forwarded them to others, officials said.

In La Crosse, Wis., a 17-year-old boy recently was charged with child pornography, sexual exploitation of a child and defamation for allegedly posting nude photos of his 16-year-old ex-girlfriend on his MySpace page. The girl had taken the pictures with her cell at her mother’s home and e-mailed them to the boyfriend.

Psychologists said the phenomenon reflects typical teenage hormones and lack of judgment, with technology multiplying the mischief. It also may reflect a teen penchant for exhibitionism, as demonstrated on MySpace and other Web sites.

In suburban Syracuse, N.Y., several teenage girls sent naked pictures on their phones to their boyfriends, only to learn that another boy had collected them from the Web and was trying to sell a DVD of them.

Some boys are photographing themselves, too. In Utah, a 16-year-old was charged with a felony for sending nude photos of himself over a cell phone to several girls.