That's what Shi'i said
The Muslim variation of the phrase "that's what she said". It is used as a joke when someone accidently uses a sexually suggestive phrase. This is, of course, ironic, seeing as a devoted Muslim wouldn't use a phrase like "that's what shi'i said" anyway.
Abdul: That thing is huge!
Achmed: That's what shi'i said!
Abdul: Last night was awesome.
Achmed: That's what shi'i said!
Achmed: That's what shi'i said!
Abdul: Last night was awesome.
Achmed: That's what shi'i said!