Foam.

(figuratively) Unimportant or insubstantial talk, events, or actions; drivel.

The idle rich.

(business) Highly speculative investment.

(transitive) To create froth in (a liquid).

(intransitive) (of a liquid) To bubble.

(transitive) To spit, vent, or eject, as froth.

(intransitive) (literally) To spew saliva as froth; (figuratively) to rage, vent one's anger.

(transitive) To cover with froth.