to quickly and easily make things up, (particularly when it comes to the definitions of words); bullshit out of reflex
John: People who use big words to describe simple things are sesquipedalian assholes.
Nicole: What does sesquipedalian mean?
Ern: Isn't it like a 70 year old squid?
Harvin: Erin, ad-glib much?
John: Ern, your retarded.