[put] in {one's} two pennyworth

to express one's opinion, even if it is not asked for

The customer put in his two pennyworth about the new store policy, even though no one asked for his opinion.
The politician put in her two pennyworth about the debate, even though she was not a member of the panel.
The armchair quarterback put in his two pennyworth about the play call, even though he was sitting at home watching the game on TV.
The know-it-all put in their two pennyworth into every conversation, even when no one asked for it.
The unsolicited advice from the stranger put my two pennyworth into perspective.