Before the NCAA came in and ruined the fun, Twitter hashtags were popping up on football fields; starting with Mississippi State's #HailState in the end zones back in 2011, followed by Michigan's #GoBlue during their Spring game a few years ago. However, helmets have remain untouched by the trend.
Leave it up to a Division III program to change that.
St. Scholastica, a D-III school in Minnesota, has become the first college football program in the country (at least that I'm aware of) to put hashtags on their helmets, placing a small #sucCeSS sticker on the back of their lids. The capitalized CSS stands for College of St. Scholastica.
I hate to say it, but it's only a matter of time before the NCAA intervenes on this as well.
Update>>Grand Valley State (D-II - MI) featured a hashtag on the back of their helmet in 2012, and will be doing the same this season. (H/T Michael Pannone). I stand corrected.