Making a claim or offering an opinion on a subject for which you have absolutely no experience or knowledge; Talking out of your ass; Derived from the surname Trump for obvious reasons. Always capitalized to distinguish from the homonym trumping.
Whereby all words spoken sound just like farts being unleashed. It is often seen in those who enjoy speaking for the sake of hearing their own voices; those who use superfluous words for the sake of using them, are also accused often of trumping.