Talk Block
verb:

occurs when one is trying to catch up with a friend and discuss dirt, but said friend's significant other enters the room and conversation must shift to "appropriate" topic so as not to upset the significant other or lead to unwanted interrogation. Significant other has "talk blocked" your conversation. Talk Blocker may also be any third party who walks into a conversation that the original parties do not want to share info with.
We were laughing about the parties we went to in college when her husband came in and talk blocked everything.

I couldn't wait to talk about what I wanted to do to him, but then his sister showed up and talk blocked, and we got stuck discussing her kids for an hour.