Source : Webster's Revised Unabridged Dictionary (1913)

Pop \Pop\, v. t.
   1. To thrust or push suddenly; to offer suddenly; to bring
      suddenly and unexpectedly to notice; as, to pop one's head
      in at the door.

            He popped a paper into his hand.      --Milton.

   2. To cause to pop; to cause to burst open by heat, as grains
      of Indian corn; as, to pop corn or chestnuts.

   {To pop off}, to thrust away, or put off promptly; as, to pop
      one off with a denial. --Locke.

   {To pop the question}, to make an offer of marriage to a
      lady. [Colloq.] --Dickens.