"Wert on lookout" is a phrase that is derived from the Old English "weard", which meant "a watcher or a guard". The word "wert" is a contraction of "were" and "thou". It is commonly used in Shakespearean plays to mean "you are" or "you were". The pronunciation of "wert" is /wɜːt/ in IPA phonetic transcription. The spelling may seem unusual to modern English speakers, but it reflects the way words were pronounced in the past.