Last season Celtics point guard Isaiah Thomas finished with 14 technical fouls, the second-highest total in the NBA. He was not pleased, but he knew that emotions can run high in a basketball game, and sometimes he could not help himself.

Before this season began Thomas’s mother, Tina, and wife, Kayla, made a friendly wager with him. They bet that he could not go the entire season without collecting five technical fouls. Thomas is never one to turn down a challenge, and this one seemed simple enough.

He could still lose his cool; he just couldn’t lose his cool as often. But then the games began and calls or no-calls Thomas disagreed with began to flow. He picked up his fifth technical foul and did not stop there.

“Yeah, it’s a wrap for that,’’ Thomas said of the family bet. “They definitely didn’t believe me and they were right, so I’ve just got to do a better job.’’

In the Celtics’ loss to the Bucks on Wednesday, Thomas was called for his 13th technical foul of the season, tied for the fourth most in the NBA. If he receives three more during the regular season, he will receive a one-game suspension.

Since there are just six games left, that prospect seems unlikely. But Thomas is aware of it. He said he is appealing the technical he received against Milwaukee.

“That should erase one at least,’’ he said. “I’m not going to do any harm to my team. I’ll be all right. I know where I’m at.’’

Mostly, Thomas said, he wants to tone down the technicals because he knows they do not set a good example for his young sons, James and Jaiden. When the two boys play games of one-on-one against each other, Thomas serves as the official, and he witnesses what it is like to be on the other side of the whistle.

“When I ref their games at home they yell at me,’’ Thomas said, smiling. “I remember the other week they said, ‘Well, you yell at the refs.’ They’re watching everything. So I’ve definitely got to do better.’’

Bradley stays home

Guard Avery Bradley will miss the Celtics’ game against the Knicks on Sunday due to a lingering stomach illness that has sidelined him for two of the past four games. Bradley did not travel with the team to New York on Saturday.

He missed Boston’s win against the Pacers last Friday before returning to play against the Heat and Bucks. But then he had a recurrence of the illness and did not play against the Magic on Friday.

Yabusele impresses

Celtics first-round draft pick Guerschon Yabusele had a successful debut with the Maine Red Claws on Friday night, tallying 17 points and 9 rebounds in 25 minutes in the the D-League’s team’s loss to Greensboro.

Yabusele was selected with the 16th overall pick of last June’s draft and spent this season playing for the Shanghai Sharks of the Chinese Basketball Association.

Yabusele just recently arrived in Maine, but other Celtics prospects have been thriving there for much of the year. Abdel Nader, the 58th overall pick last June, is averaging 21.5 points, 6.2 rebounds, and 3.9 assists per game. He was selected to play in the D-League All-Star game last month.

“He had a great season,’’ Red Claws coach Scott Morrison said. “I think he’s really improved and opened some eyes. Like everybody else, I’m sure he’s struggling a little this time of year with the length of the season and the crazy travel. But he’s still attacking the rim and he’s still finishing well.’’

The Celtics hold Nader’s draft rights, and he has made no secret about his desire to make the final roster next season.

Demetrius Jackson, who was selected by Boston with the 45th overall pick last June and then signed to a partially guaranteed four-year deal, has spent most of this season in Maine, too. He is averaging 14.9 points, 5.9 assists, and 5.1 rebounds per game, although he has made just 27.9 percent of his 3-point attempts.

“He’s improved, and he’s doing a good job of getting into the paint and he’s started to shoot the ball better after a slow start,’’ Morrison said. “We’re also focused on him being disruptive on the ball and making things tough on the opponent.’’

Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him on Twitter @adamhimmelsbach.