The little two-word chat that you initiate with someone while waiting for other interesting people to reply (or a video to finish loading) and which you don't bother going back to as soon as the interesting windows start showing some action - Usually caused by restless scrolling through one's contact list during the wait
Jenny: Hey where have ya been?! I had SO much to tell ya!
*Long Gap with no reply*
Jenny: Did you just filler chat me?!