We recently produced these hashtag badges for Plan International for the International Day of the Girl. Including a hashtag on your badge is a way to encourage social media engagement especially at events. The hashtag badges can be an effective nudge suggesting to your audience that they share images or thoughts online. A hashtag specific to your event, cause or product also helps the audience to find other people's social media responses by uniting it under a single tag.
I have attended events in the past where visitors were tweeting or tagging Instagram posts with four or five variations of a hashtag. These badges eliminate while also communication the spirit and message behind the International Day of the Girl.