whet one's appetite
Arouse one's interest or eagerness, as in That first Schubert piece whetted my appetite; I hope she sings some others. This idiom, first recorded in 1612, transfers making one hungry for food to other kinds of eagerness.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.