Sarcasms are when someone says the opposite of what they really mean, usually to be funny or to show that they are not happy.
Sarcasms can be funny, but they can also hurt someone's feelings if they are not used carefully.
Examples:
She said 'Oh, great!' with sarcasms when she saw the mess.
His 'Thanks a lot' was full of sarcasms.
When she said 'You're so helpful' with sarcasms, I knew she was not happy.
His 'Nice job!' was full of sarcasms.
Their sarcasms made everyone laugh.
The sarcasms in his voice made me feel bad.