On January 8th 1978 the Sex Pistols played Randy's Rodeo in San Antonio, Texas to a sold out crowd of roughly two thousand. This was the third date of their American tour, two days later they played Dallas, which was the extent of their appearances in Texas. The Dallas show is great and you can find footage of that show in its entirety online. But the show at Randy's placed the band in a much more hostile environment- the audience was a truly strange assortment of early Texas versions of punks (basing their look on major media reports on the music, many still with beards!), along with rednecks, freaks, cowboys, and Mexicans. The audience bootleg I've uploaded is of rough quality but it definitely gives you a feel for the electric atmosphere of the show.
San Antonio was the gig where Sid took his bass off and hit somebody in the head with it, which you can see at the end of the clip below. McClaren's decision to have the band avoid their major markets on both coasts and instead play Texas and the South was a stroke of genius, at least from the stand point of maximizing confrontation, thereby giving the band something challenging to play off of - a real culture clash.