No, it's not in South Park, Colorado, but in Adelaide, Australia:
Gay dogs not welcome, diner told | Adelaide Now
Note that it is possible for the phrase "guide dog" as pronounced in a refined sort of Australian accent to sound very like the phrase "gay dog" as pronounced in a broad Australian accent only by the duration of the [d] in the middle--in IPA notation, [gaɪd dɒg] vs. [gaɪ dɒg].
Gay dogs not welcome, diner told | Adelaide Now
A RESTAURANT that refused a blind man entry because it thought his guide dog was "gay" has been ordered by the Equal Opportunity Tribunal to pay him $1500.
Woodville North man Ian Jolly, 57, was barred from dining at Grange restaurant Thai Spice in May last year after a staff member mistook his guide dog Nudge for a "gay dog", the tribunal heard this week.
A statement given by restaurant owners Hong Hoa Thi To and Anh Hoang Le said one of the waiters had understood Mr Jolly's partner Chris Lawrence "to be saying she wanted to bring a gay dog into the restaurant".
Note that it is possible for the phrase "guide dog" as pronounced in a refined sort of Australian accent to sound very like the phrase "gay dog" as pronounced in a broad Australian accent only by the duration of the [d] in the middle--in IPA notation, [gaɪd dɒg] vs. [gaɪ dɒg].