A sink plug decides whether water stays or drains away, so it is read as holding on or letting go. Pulling it stands for release; a lost plug, for feelings that will not stay put.
Where in your waking life have you met something like this lately?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.