Let's put the eggs in sacks

The story:

My sister was a big Kiss fan and played this on a tape for me. I sat there with this really puzzled look on my face and said 'Isn't that really stupid? I mean, they would break, wouldn't they?'
My sister repeated the title for me ever more precisely and slowly, laughing harder and harder, and by the fifth time she was sliding off the sofa in tears. I think in the end she had to write it down.
I'm not normally this dumb, honest.