1The argument was over a petty issue, but it still managed to ruin the party.
2She's being petty by refusing to lend me her book just because I forgot to return it last time.
3The company is being petty by charging customers extra for every little thing.
4The politician's opponents accused him of being petty and vindictive in his response to criticism.
5Don't be petty and hold grudges; just forgive and move on.