Last year my husband picked up this sweatshirt on a super sale for like $2. The problem was that it was a wee bit too small in the neck, so I couldn't really get it over my head. After letting it sit at the bottom of my drawer for a year, I pulled it out to see if I could make it work.
Here are the settings on my Janome 423s--I actually ended up using the buttonhole setting--without the buttonhole foot, of course.
I stitched it so that the purple line was not touched by the thread--I didn't want any chance of accidentally overlapping my stitches or cutting them when I opened up the neckhole.
I cut it, cleaned it up a bit with my scissors...
And tried it on! Sorry about it not being a full picture, I didn't fix my hair today, so this will have to do. :)