go mental

/G OW1 M EH0 N T AH0 L/
verb
  1. 1

    To become extremely angry.

    โ€œHer father went mental when he found out that she was pregnant.โ€

  2. 2

    To become wild with excitement.

    โ€œWhen the band came on stage, the crowd went mental.โ€

Source: https://en.wiktionary.org/wiki/go%20mental