The party was in full swing.

Meaning

The party was lively and at its peak.

Examples

• John: 'How was the wedding reception?'<br>
• Alice: '<b>The party was in full swing</b> by the time I arrived.'
• John: 'Me too! <b>The party was in full swing</b> when we left.'
• Alice: 'I wish I could've stayed longer at the New Year's Eve party.'<br>