2nd Monitor going Bonkers.
The 2nd monitor for my iMac started doing squiggly lines. It's a new iMac (replacement) but I've never had this issue.
http://i.imgur.com/uo4gRaG.gif
for reference.
try changing the cable or the direction of the cable (monitor end in mac, mac end in monitor) if the problem persists reset the lcd to factory defaults, try another resolution and if that does not change run a HW diagnostic
Using Apple Hardware Test - Apple Support
Honestly, if it's a new mac take it back to apple store and have them do a diagnostic on the computer if it's under warranty.
p.s. dont **** up your marriage holmes.