Don’t forget Rrose Sélavy (though in that case not each letter is spelled out). Rrose Sélavy connaît bien le marchand du sel…
O sibili, si ergo, fortibus es in ero ?
Dem is no buses; dem is trucks!
Mairzy doats and dozy doats and liddle lamzy divey
A kiddley divey too, wouldn’t you?
I always thought that the bolded was “wooden shoe”, which seems much more clever.
Yes, someone versed in Classical languages gave me an example of such a pun. I believe it was a spelling of a Latin word that ended up sounding like the song’s lyrics. Which is even more funny because the song’s lyrics are deliberately a punning rhyme.
You want to see the masterpiece of the genre, look for Mot d’heures: Gosses, Rhames by Luis d’Antin van Rooten.
It’s a series of what seems like poetry in French but when you read it aloud, you’ll realize – well, it’s exactly what the title says.
For example:
Un petit d’un petit
S’étonne aux Halles
Un petit d’un petit
Ah! degrés te fallent
Indolent qui ne sort cesse
Indolent qui ne se mène
Qu’importe un petit d’un petit
Tout Gai de Reguennes.
Then there’s:
Lit-elle messe, moffette
Satan ne te fête,
Et digne somme coeurs et nouez.
À longue qu’aime est-ce pailles d’Eure.
Et ne Satan bise ailleurs
Et ne fredonne messe. Moffette, ah, ouais!
He manages about 50 of these.
I’m glad you did because I kind of suck at Spanish, but I knew what the answer to the joke was just as soon as I sounded it out.
I wonder if it’d work equally well in all dialects of Spanish though. I had a Mexican co-worker act as a translator with a Chilean customer, partly because I couldn’t understand a word the customer said. Even when I was listening to them talk, I’d hear completely comprehensible Spanish, and the reply would sound nothing like Spanish to me, much less being able to figure out what words were being said. My co-worker felt largely the same way, “this guy’s accent is killing me” was said privately to me several times.
Yes it would. In seseo (the dialects with most speakers, where most /θ/ turn into /s/ if between vowels or disappear if at the end of a word), ejeo (turns /s/ before plosive into /x/, aka “the throat-clearing sound”) and standard Spanish (the dialects on which our spelling rules are based) the English pronunciation and the Spanish pronunciation are very close (ejeo would turn one of the /s/ into /x/, exto sí ke es); some English dialects would have vowels which are a bit different from the Spanish ones, and one family of Spanish dialects would pronounce some of the /s/ as /θ/ (ceceo), but in no case would the difference be so large as to make the pun not work. It would stil be groan-worthy, but well, it’s groan-worthy regardless of accent 
In Spanish we just call those bromas bilingües (bilingual puns); the never-linked enough video Trump Mamón contains trilingual jokes (commentary here).
Thanks, Nava! I’ll need to read up on phonetics before I understand much more than “Yes it would”, but it’s nice to know the one Spanish joke I know will work in a universally poor way. 
/s/ is usually represented both in Spanish and in English by the letter “s”: Spain, sound
/x/ is represented in Spanish by “j” (followed by a, o, u) or “g” (followed by e, i): Jaime, Genaro, Gil, José, Juan; English only has it in words acquired from other languages such as Scottish loch or Hebrew Chaim (see wedding scene in Fiddler in the Roof), or the aforementioned Spanish names when their original pronunciation is respected
/θ/ is represented in Spanish by “z” (followed by any vowels) or “c” (followed by “e” or “i”), but in seseo it becomes /s/ and most speakers in your location are seseo speakers; in English it’s confusing because it’s one of multiple sounds represented by the digraph “th”, and when is that digraph pronounced which way varies by dialect. But, aha! Saragossa’s City hall to the rescue! Or, as we write in Spanish, Zaragoza. The very first word in this video contains that sound twice
Hehehee, thanks, and thanks for the free Spanish pronunciation lesson!