1. Buy her a cell phone.
2. Set it up.
3. Make her practice sending Text Messages with it.
4. When she sends you a message to your cell from your website, text her cell phone back to tell her you got the message.
5. Before you leave the house, don't tell her you left her cell phone on the kitchen counter, turned on, and when she's sitting at the computer, quietly minding her own business in what she thinks is an empty (but for her) house, the cell phone, without any beeps or warning whatsoever, will proclaim to all and sundry that "A Message Has Been Received"
Trust me. It will totally freak her out.