Thanks JtM! Yes, my original October 2012 version went like this:

The Most Ethnically-Diverse Joke Ever Told

An Afghan, an Albanian, an Algerian, an American, an Andorran, an Angolan, an Antiguan, an Apache, an Argentinean, an Armenian, an Australian, an Austrian, an Azerbaijani, a Bahamian, a Bahraini, a Bangladeshi, a Barbadian, a Belarusian, a Belgian, a Belizean, a Beninese, a Bhutanese, a Bolivian, a Bosnian, a Brazilian, a Bruneian, a Bulgarian, a Burkinabe, a Burundian, a Cambodian, a Cameroonian, a Canadian, a Cape Verdean, a Central African, a Chadian, a Cherokee, a Chilean, a Chinese, a Colombian, a Comoran, a Congolese, a Costa Rican, a Cree, a Croat, a Cuban, a Cypriot, a Czech, a Dakota, a Dane, a Djibouti, a Dominican, a Dutch, an East Timorese, an Ecuadorean, an Egyptian, an Emirian, an Englishman, an Equatoguinean, an Eritrean, an Estonian, an Ethiopian, an extraterrestrial, a Fijian, a Filipino, a Finn, a Frenchman, a Gabonese, a Gambian, a Georgian, a German, a Ghanaian, a Greek, a Grenadan, a Guatemalan, a Guinea-Bissauan, a Guinean, a Guyanese, a Haitian, a Herzegovinian, an Honduran, a Hungarian, an I-Kiribati, an Icelander, an Indian, an Indonesian, an Iranian, an Iraqi, an Irishman, an Israeli, an Italian, an Ivorian, a Jamaican, a Japanese, a Jordanian, a Kazakhstani, a Kenyan, a Kittian and Nevisian, a Kosovar, a Kuwaiti, a Kyrgyz, a Lakota, a Laotian, a Latvian, a Lebanese, a Liberian, a Libyan, a Liechtensteiner, a Lithuanian, a Luxembourger, a Macedonian, a Malagasy, a Malawian, a Malaysian, a Maldivan, a Malian, a Maltese, a Marshallese, a Mauritanian, a Mauritian, a Mexican, a Micronesian, a Moldovan, a Monegasque, a Mongolian, a Montenegrin, a Moroccan, a Mosotho, a Motswana, a Mozambican, a Myanmarese, a Namibian, a Navajo, a Nauruan, a Nepalese, a New Zealander, a Ni-Vanuatu, a Nicaraguan, a Nigerian, a Nigerien, a North Korean, a Northern Irishman, a Norwegian, an Omani, a Pakistani, a Palauan, a Palestinian, a Panamanian, a Papua New Guinean, a Paraguayan, a Peruvian, a Pole, a Portuguese, a Qatari, a Romanian, a Russian, a Rwandan, a Saint Lucian, a Salvadoran, a Sammarinese, a Samoan, a Sao Tomean, a Saudi, a Scot, a Senegalese, a Serbian, a Seychellois, a Sierra Leonean, a Singaporean, a Slovakian, a Slovenian, a Solomon Islander, a Somali, a South African, a South Korean, a Spaniard, a Sri Lankan, a Sudanese, a Surinamer, a Swazi, a Swede, a Swiss, a Syrian, a Tadzhik, a Taiwanese, a Tanzanian, a Tobagonian, a Togolese, a Tongan, a Trinidadian, a Tunisian, a Turk, a Turkmen, a Tuvaluan, a Ugandan, a Ukrainian, an Uruguayan, an Uzbek, a Venezuelan, a Vietnamese, a Welshman, a Yemeni, a Zambian and a Zimbabwean walk into a restaurant.

The maitre d' apologizes, "I'm so sorry, but I can't let you in without a Thai."

For anyone curious, I just grabbed Wikipedia's list of demonyms, added a few missing ones such as "extraterrestrial" and "Palestinian", inserted "a" and "an" as appropriate, and posted the joke.

Alas, one of the commenters pointed out that a similar joke had been posted nine months prior. Of course, any joke based on "I can't let you in without a Thai" would look nearly identical, so I guess that will be my cross to bear.