Though the stickers were designed by the Fort Bend County Democrats, Fonseca and her 12 kids have jumped in on the cause and started to sell the decals for $15 a piece.
The demand for the hot-ticket item is intense.
"It's turned into this bigger thing, everything is back ordered," Ali Hasanali, a Fort Bend Democrats member, told local station KHOU. "We can't print enough, even if they want to buy now there's going to be a delay because we have to print a lot more up."
Now a symbol for the Democratic group, Hasanali says Fonseca represents anyone willing to stand up against politicians who abuse their power.
"My hat's off to Karen for being forthcoming and not being pressured or intimidated," Hasanali added. "She's a rallying cry for anyone who cares about individual liberties."
According to Hasanali, money raised from the decal sales will go toward a voter registration drive that will help get elderly voters to the polls.
Fonseca later told the station that she also plans on selling a new decal: "F*CK TROY NEHLS AND F*CK YOU FOR VOTING FOR HIM" for the same double-digit price. The decal is currently placed right next to the anti-Trump sticker on her truck.
Fort Bend County Sheriff Troy Nehls later said he was "not surprised" by the new addition and that he found it "somewhat disgusting."
"I never chose to be in the news at all," Fonseca told reporters Tuesday, "until Troy Nehls made it public on his personal Facebook page."
The Fonseca family gained overnight fame after Nehls took to his official Facebook page to threaten legal charges against the owners of the truck. The Texas sheriff stated that the station's prosecutor "would accept disorderly charges regarding [the F*ck Trump sticker]."
Though the official later backed down, he informed critics that he was merely concerned with preventing a potential road-rage incident triggered by the sticker.
Days after the story went viral, Fonseca was arrested for an outstanding warrant dating back to 2014. She was later released on bond.
"I'm almost certain it does have to do with this," Fonseca told the media after posting bail. "People abuse the badge, and in my opinion, money talks. When you're in politics, people know how to work the system."
Speaking at a news conference Monday, Fonseca said that she is considering a civil rights lawsuit against the sheriff "regarding the injustice against" her.