pushpin

Short definition from Wiktionary

Noun

1. 1
   A small pin with a head made for gripping with the fingers, to be pushed into a bulletin board so as to pin papers to it; especially, such a pin with a cylindrical head.
2. 2
   An old children's game where pins are placed on a table and each player tries to push his pin so as to cross the other's.

Verb

1. 1
   To fasten with a thumbtack.