It’s about time. We are now on Instagram!
1590s, "smooth and slippery," possibly a shortening of obsolete glibbery "slippery," which is perhaps from Low German glibberig "smooth, slippery," from Middle Low German glibberich, from or related to glibber "jelly." Of words, speakers, etc., from c.1600. Related: Glibly; glibness.