Josh Brown on Sonic: He likes it!

Sonic is set to report third quarter earnings after the closing bell Monday afternoon. Shares of the fast food chain are up more than 20 percent year to date. Compare that to McDonald's which is up only 3 percent so far this year.

CNBC contributor Josh Brown is Fast Money Halftime Report's unofficial food correspondent. Lately he's been watching Shake Shack closely but said Sonic is actually a much more fierce competitor to McDonald's.

Brown, CEO of Ritholtz Wealth Management, said the line is always full when he passes, or eats at, a Sonic and that and same-store sales reveal it's one of the fastest-growing burger joints in the country. Last quarter the company's same-store sales jumped 11.5 percent. Sonic's guidance this time expects "low to mid-single digit" growth in the category.

According to FactSet, analysts expect $0.36 earnings per share and revenue of $163.8 million.

Jon Najarian, OptionMonster founder & CEO is watching Sonic's shrinking drive-thru business as a positive indicator. "When you get people to come inside, their tickets are bigger," Najarian said.

"I would not want to be short this name going into earnings tonight," Brown Said.

A Sonic drive-in restaurant is shown in Normal, Ill.
Daniel Acker | Bloomberg | Getty Images
A Sonic drive-in restaurant is shown in Normal, Ill.