San Francisco 49ers quarterback Colin Kaepernick — who leaped into national headlines when he decided to sit out the national anthem in August to protest violence against people of color — received a stunning reception at a game Sunday against the Buffalo Bills.

T-shirts depicting the star quarterback with a rifle scope trained on him appeared on Twitter, declaring Kaepernick a "notorious disgrace," and were on sale outside the Bills' stadium in Buffalo, New York.

Another T-shirt taunted the football player by referring to him as "Kaeperdick" and avised him to "Shut up and stand up!"

The image had been liked more than 1,400 times on the social media platform by late Sunday afternoon.

These weren't the only anti-Kaepernick sightings outside the Bills' stadium, either.

Buffalo Bills running back LeSean McCoy had asked Bills fans to be "respectful" and "professional" toward Kaepernick at Sunday's game, but it seems like some fans didn't listen. These shirts were also spotted for sale today outside the New York stadium:

A video posted by sports reporter Robert Klemko on Twitter captured a group of Bills fans yelling, "Tackle the Muslim!" around a dummy in a Kaepernick jersey and an Afro wig; a young woman obliged.

Someone may have even thrown a bottle at Kaepernick from the sidelines:

This behavior isn't as surprising as it seems.

Buffalo has a long history of racial division off the field.

• As of 2010, the city was still ranked as the sixth most segregated metro area in the United States.
• A study found that Western New York may be one of the most racist places in the United States, based on residents' Google searches.

"Buffalo might be the most racist city in the North," Rashad Brown, a 38-year-old Bills fan, told SB Nation in August.

(Not all Buffalo residents or Bills fans can be considered racist, of course, and one group of locals calling themselves "Just Resisting" gathered outside the stadium on Sunday and took a knee when the national anthem played to show their support of Kaepernick, WIVB reported.)

The NFL has also been accused of racism, which helps explain the anti-Kaepernick expressions on Sunday.

More Black players are taking on key positions such as quarterbacking in the NFL, and "certain people can’t adapt to having someone of color in control," Brown added. "And when they do excel, they have to be three to four times better. The NFL is like this. They don’t have the same culture as the NBA. This isn’t a Black league. The whole feel here is different."

Consider:

• People of color average only a 2.6-year career in the NFL, while all players taken as a group may average anywhere from 3.3 to six years of play.
• Some critics have suggested that this is because a person of color can "anger the wrong person, teammate, or executive, and players run the risk of shortening their [careers]."
• Black football players are also often pigeonholed into certain positions based on racial stereotypes in a practice known as "stacking."

Stacking refers to the belief that white athletes are better in "thinking" roles, such as quarterback, while people of color are more suited to "athletic" roles, such as running back. More than 90 percent of running back, cornerback, and receiver positions in the league were occupied by Black men as of 2009, according to one report. White men, meanwhile, made up 81 percent of starting quarterbacks.

For the its part, the NFL has not directly commented on charges of racism in the league, but NFL Executive Vice President Troy Vincent has said previously that "football transcends race, age, gender, and other elements of society" and cast the sport as something that "creates community by bringing people together."

The league has also supported Kaepernick's right to protest, saying simply: "Players are encouraged but not required to stand during the playing of the National Anthem."

Not everyone agreed with the anti-Kaepernick displays.

Some Bills fans responded with outrage and sadness to the T-shirts.

Kaepernick continued his protest Sunday by taking a knee during the anthem.

That didn't bother one Bills fan.

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