Rectangular aluminum keys?

I had a dream that involved the Cal Band... and my boss.

I did something (can't remember) pretty intense for the Band, and when I'd finished it, it was time to go into the stadium with them. But, as I pointed out to my boss (not IRL in the Band), I didn't have my 'horn' (I think I've called my piccolo that maybe twice in my life, even though it's the standard terminology in the Band) and needed to go home.

To come back, I'd need keys, so he hands me this huge wire loop (somewhat similar to the loop that my water polo teacher uses for the water polo caps, come to think of it) with maybe 25 aluminum rectangles on it. Each rectangle is much like the others, with subtle differences in the stick-figure diagram on it. Apparently, I need the whole keyring.

I go home and get my picc and music, and come back and park close to the stadium. (Now you know it's a dream!!) I think I had to place one of the appropriate triangles into a recession to get in.

Dreams are so weird.