Muppet

Etymology
From Muppet, possibly suggesting that the person needs to be directed by others. Allegedly coined from initial letters of "The most useless person Pirbright ever trained". Pirbright being an MOD army camp. Although, Jim Henson's usage is said to be a combination of marionette and puppet.

Noun

 * 1)  An incompetent or foolish person.
 * Sally is such a muppet, the way she always gets George coffee.

muppet