When you back slide into old, bad habbits that you are known for. The same bad habbits that you swear to everyone you have given up forever. As used by the title character in the Netflix series Better Call Saul.
"This is not what you think! I am not Slippin Jimmy anymore!"
"It wasn't my fault that I was late for work! I'm not a Slippin Jimmy! I haven't been late in weeks!"
"I'm just gonna have one drink. I'm not gonna turn into a Slippin Jimmy."
Employee: I have been using a wheelie-walker for five months, and I keep being promised a ramp will be installed
Boss: Oh, it's not in this year's budget
Employee: Failing that, I'll be doing a "Slipping Jimmy". I did actually fall a over at home negotiating the bathroom. Can't really sue myself, alas.