Why does this amuse me so?

[diziara]

him: I'll give it a shot but if I get lost, crash, and die it's your faoult :|
me: I love how there's an o involved in the fault. :-P
him: im so tired D:
him: haha
him: that typo is your faoult :p
me: all fault should involve an o. Should be a big one though.
him: faOult