Hmmm, while I believe a punch in her face would be the best thing for your soul, have you thought about something truly scary, but probably not too easy to do, unless you have access to her PC... like installing in her pc a freeware Windows NT/Windows XP remote controlling software. Basically, if you have access to her pc, you would just need to install the thing in her pc, and when she goes online, you can control her Pc remotely from your home, doing nice things like moving her mouse cursor, and writing oh so funny lines in her Internet browser address field, like "I am going to punch you in the face", or "I am your grandma's ghost".
Wouldn't it be nice? And it is really doable...
https://www.realvnc.com/