Some random ideas...
Navy or black t-shirt with stars... constellations forming the N and the B, and then a crescent moon or a full moon for the O... or a comet with NBO written in the tail. I can't come up with a cute slogan tho' ...
If you're going to do name tags, make them star-shaped. You could do black with names written in gold or silver metallic pen, or gold or silver with names in black. Building on xo_kathy's idea, how about putting people's zodiac signs on the name tags?
Keep your room relatively dark and crisscross the ceiling with a bunch of Christmas lights to simulate starlight. (I know you didn't ask for decorating ideas, but I thought this might help
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Good luck with rush!