The woman was playing 'tig' with other parents and children at Brierley Forest Primary School, on March 25, last year when Ben Chadwick appeared and said: “This is how you play infinity tig.”
Rebecca Williams, prosecuting, said that when he grabbed and squeezed her breasts she pushed him away and he fell over.
Chadwick, aged 39, swore and said: “Why can’t women take a laugh?”
And when another parent told him: “You can't go around groping women on the boobs,” he swore and replied: "Why can’t women take a joke?”
Chadwick, of Lawrence Crescent, denied sexual assault on a female, but was convicted after a trial at Mansfield Magistrates’ Court.
In a statement made, his victim described how she ‘struggled’ in the aftermath of the incident, and said her son was worried about her walking home alone.
She said she experienced anxiety and sleeplessness, and the sight of Chadwick around town had triggered panic attacks.
Ms Williams said the offence was aggravated because it happened in front of schoolchildren and Chadwick ‘thought it appropriate to draw their attention to what he was doing’.
She also said the comments he made were a cause for concern.
Neil Taylor, mitigating, said Chadwick, who lives with his parents and works as a team leader at a supermarket, has no previous convictions.
He said: “Clearly he demonstrated some very poor thinking skills. It was spur of the moment. While he may have meant that as some sort of joke it wasn't taken as such by the victim.
“It’s clearly a big jump to having a conviction for a sexual offence.
“He hasn’t attended that school since. It is 15 months since the incident. This isn't something that has been planned. The touching was brief and over clothing.”
He received a 12-week prison sentence, suspended for 15 months on condition he does not commit another offence and complies with 30 rehabilitation days.
A restraining order was imposed and he was placed on the Sex Offenders Register for seven years. He must also pay a £128 surcharge and £620 costs.