referring to someone who interrupts a story to tell a long, pointless story that goes on mindless tangents that has nothing to do with your original story like Rose was infamous for on the Golden Girls.
i.e Sarah:"So can you believe I ran into my ex from 5 years ago in a another count-"
Michelle: "Wow that reminds of the time my cat got the flu. You see what happened was......"
Matt: "ughhh, there Michelle goes telling another back in st. Olaf story again"