[Cheerio]

Don't forget to read the stickies at the bottom of this thread, each has a few ideas in answer to your question.

Additional idea, probably best for a smaller pledge class: Each Big identically decorates, with ribbons/feathers/balloons/hot-glued beads/stickers/postcards/etc, a cheap (identical) pair of hair clips from the dollar store. This means both the Big and the Little in a pair will be wearing IDENTICAL hair clips at the reveal.

One chapter member might be put in charge of double-checking that each finished pair looks dissimilar from other pairs, or you could assign each Big a specific color and/or decoration type to use.

Distribution of decorated clips to Littles might be prior to a special Big/Little breakfast (one hour before the reveal). The Littles wear their clips during the breakfast. A short, fun ceremony to reveal each Big, wearing her matching clip, follows breakfast completion. The breakfast might be on Game Day, with optional game attendance and clips decorated in school emblems/colors. Again, this may be best for a smaller pledge class.