Hi!
Today I've seen a gag in 9gag.com about the pronunciation of scissors and as far as I know a restaurant in the States. This is the link: http://9gag.com/gag/5569980
Just in case you don't feel like seeing it, it says "How do Mexicans cut their pizza? Little Caesars". I had to look it up to discover Caesar is pronounced as / ˈsiːzər / and scissors as / ˈsɪzərz /. So I guess the joke is about the confusion of the [iː] and [ɪ] sounds. I imagine it can be somehow funny when the confusion includes words like sheet/shit, but as a non-native English speaker, I'd like to ask native English speakers: is it really so funny and so noticeable in this case?

Unfortunately, this joke also plays on the Mexican accent, which tends to pronounce <ɪ> as <i>.

Yes, I know, I'm not Mexican but I'm a native Spanish speaker so I also pronounce <ɪ> as <i> sometimes. Don't worry I'm not offended by these jokes and I don't really think many Mexican people would be offended either . In any case, it does seem a characteristic feature easy to recognize for you, doesn't it? :/ Now I think I'm never going to be able to get rid of my accent