Gamey 
It gives you gas   PUMP
Pop your pop might have liked   NEHI [also can give you gas]
Where the toys are   CHEST [sounds like “Where the Boys Are”]
Theme: compound words (phrases) each part of which can precede the word 
gameWith 40-Across, in an advantageous position…   AHEADOFTHEGAME [each of the word segments can literally be ahead of the {word} 
game: MEMORY, CARD, PAJAMA, PARTY, etc.   

This proves that Monday puzzles can be easy yet fun.  I'd vote this the best Monday puzzle of 2010.
RATING:
Three grins = Excellent: Loved it; Two grins = Good: Enjoyed it; One grin = Satisfactory: A bit bland for my taste; One teardrop = Unsatisfying: No fun