Athingamatism
When a person can't think of the names of objects/people and uses 'thing' instead of the proper name, usually done in excess
"Can you go take your...uhh...'thing' for a walk now?"
"You mean my dog?"
"Yeah, sorry, it's my athingamatism acting up again."
"You mean my dog?"
"Yeah, sorry, it's my athingamatism acting up again."