Ack...I just realized she said infinity scarf. You're right, GG, but see my comment below.
So waffle are you following a pattern? I'm assuming its a big long loop. In this case you can do a 3 needle bind off by not binding off the other end and putting the provisional stitches on on a needle to 3 needle bi d off. However I would probably try to use Kitchener stitch if possible. Then you do t have the ridge created by 3 needle bind off and it does look like an infinite loop.