Matching Pairs IDIOMS. AGEOnline version IDIOMS. AGE by María Marteles 1 to be knee-high to a grasshopper 2 (be) over the hill 3 silver surfer 4 (live to a) ripe old age 5 to act your age 6 feel your age 7 get on in years 8 long in the tooth 9 mutton dressed as a lamb 10 rob the cradle Too old to do something Reach an age when you can no longer perform as well as before. An elderly person who uses the internet To live until you are very old. a person who tries to look younger by wearing clothes designed for younger people Someone who is growing old. Have a romantic relationship with someone who is much younger than yourself. Realize that you are no longer young no to behave as someone younger Very young or small child