You Cannot Be Serious, # 30

From a Travelodge poster on the London Underground:

Oxford Dictionaries confirms that this spelling hasn’t been acceptable since the Middle Ages, and proves a brief history of the word and its relation to until. (Unfortunately, its own examples of abbreviated usage include an open inverted comma in place of an apostrophe…) Oddly, both MS Word and Corel WordPerfect include til in their spelling dictionaries, although Word does flag it as an error if the US-English dictionary is selected.

til for till