On Wednesday 15th October Hong Kong's chief executive Donald Tsang Yam-kuen delivered his policy address. During that policy address, he took a few seconds to comment on the sentence " Bow Tie Keep Your Election Promise", suggesting that one 's' should be added to the end of the word 'Keep'. According to my understanding, in this is sentence, the verb form is called 'imperative' in grammar. There are two types of 'imperatives'. Affirmative imperatives have the same form as the infinitive without to, while negative imperatives use do not plus infinitive. One example of imperative sentence is 'Enjoy your holiday', or 'Have some more tea'. The imperative sentence does not necessarily have a subject, but we can add one to it for the sake of clarity. For example 'Mary come here.', or 'Bow Tie come here.', or 'Bow Tie shut up.', or 'Bow Tie Keep Your Election Promise.' All these sentences are perfectly correct grammatically.
Michael Swan. Practical English Usage. Oxford University Press, 2002.