jail: a place of confinement for individuals who have been convicted of a crime, usually a more severe form of punishment than other options.
that's a bit stiff: this phrase suggests that the idea or statement is a bit too harsh or severe. in this context, mary is expressing her opinion that sending someone to jail might be too severe a punishment.
lying around: if something is "lying around," it means it's left in a place without being properly stored or secured. in this context, rachel is questioning whether jaz left his phone unattended.
wrongdoers: individuals who have committed a wrong or engaged in inappropriate or unlawful behavior. mary uses this term to refer to those who commit crimes.
i'm all for: this phrase is an expression of strong support or agreement. in this context, jaz is expressing strong support for expulsion or a long suspension, indicating a preference for such consequences.