While riding the subway in Shanghai last week, I glanced at the TV playing some commercials and saw what looked like a slightly off spelling of the city's name (上海). I could not get a very good look (and my area of [limited] expertise is kanji, not hanzi), but I am pretty sure the second character was: 嗨 (instead of 海).
When I looked it up in my Mandarin dictionary, sure enough '嗨' had a similar pronunciation, and a meaning ('alas', but also slang for 'hi!', according to that dictionary) that seemed to make it a pretty good fit for a pun on 上海.
However, the tone seems to be different:
上海 [shàng-hǎi] vs. 上嗨 [shàng-hāi]
To my limited understanding, this would make the two words completely different to a native Mandarin ear...
My question is therefore:
To a regular Mandarin speaker, would 上嗨 sound close enough to 上海, to work as a pun? Would it only work as a visual pun (and not so much when read aloud)? Neither?