This shit drives me up the wall even more than "unalive"
You can't stop people saying slurs but an entire generation will subconsciously alter their entire vocabulary because they grew up on corporate platforms with very heavily moderated text chats and comment sections and they ended up internalising the filters 
Edit: I was not aware of the AAVE origins of "ahh" which pushes it more towards the territory of legit slang. Still, I stand by my general point about automated moderation influencing language being bad
From the Soulja Boy song I linked in another comment, evidently it's just pronounced /æ(ː)/ — so it rhymes with yeah, nah, and baa, when these words are pronounced with the TRAP vowel. What's interesting is that /æ/ (TRAP vowel) is a checked vowel, and I have to wonder if that's what allowed the /s/ to be dropped from ass in the first place: if the vowel already tells you that the next sound must be a consonant, then the consonant itself becomes a bit redundant. The other notable words that get the same treatment are bih and shii, which also have checked vowels. But I'm no AAVE linguist.
Edit: Yeah, in "Crank That", Soulja Boy also very prominently elides the ends of words with free vowels, so I guess the checked vowel thing might've just been me noticing a pattern that wasn't actually there. But who knows, maybe there's internal variation — it's not my dialect, I've never even been to the South where this sort of elision is most widespread.
Guess I'm confused because I see "ahh" and I read it as the a in "far" not as the a in "ass"
As I'm sure most people without context would, but there isn't really a better way to spell it.