Put/stick your oar in
Definition 1 of 1
Pro Tip 1/3Social Signaling
Using this phrase hints that you find someone's interference annoying or inappropriate. 
There he goes, sticking his oar in again—it's really grating on my nerves.
Pro Tip 2/3Conversation Tone
Implies a casual setting since it's colloquial; not suitable for formal discussions. 
In our team meeting, you shouldn't put your oar in when the managers are strategizing.
Pro Tip 3/3Negative Connotation
The phrase often conveys a negative judgment towards the interjector's actions. 
She put her oar in with negative comments, unwelcome by everyone.