Caught myself doing this while writing...?

Keep it i would say but make it specific to a character's voice. The reason why we know the popular lexicon or slang from the past is because some of the best writers were using it in the dialogue of their novels. Imagine if they had stuck to just the clical, ornamental style of writing we couldn't tell one era from the other. It is an honest representation of ones times. Language evolves, also it has the geographical tinge, it must reflect in the writing as well. It will survive criticism if the work itself has potential.