Riddle of the Day

[Gizmokid2005]

Jenn picked a book off the highest shelf in her room. On the spine she read How to Jog. She ran out of the room and opened the book but found it had absolutely nothing to do with jogging. Explain.......

ANSWER (Congrats acoustikarl): The book is an encyclopedia.

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NEXT RIDDLE:

Take away my first letter and I am unchanged;
Take away my second letter and I am unchanged;
Take away all my remaining letters and I am still unchanged!
What am I?