Although any figure of speech may be employed to evoke an emotional response, many figures are specifically designed to do so, or else are themselves functions of the emotional state of the speaker.
Why are you so stupid?
This use of epiplexis, a kind of rhetorical question, does not seek the information it ostensibly asks for, but is likely an attempt to provoke anger in the listener.
Figures used to provoke emotional response (pathos)
adhortatio (A comandment, promise, or exhortation intended to move one's consent or desires.)
adynaton (The expression of the inability of expression —almost always emotional in its nature.)
aganactesis (An exclamation proceeding from deep indignation.)
apagoresis (A statement designed to inhibit someone from doing something.)
aposiopesis (Breaking off suddenly in the middle of speaking, usually to portray being overcome with emotion.)
apostrophe (Turning one's speech from one audience to another, or addressing oneself to an abstraction or the absent—almost always as a way of increasing appeal through emotion.)
cataplexis (Threatening/prophecying payback for ill doing.)
conduplicatio (The repetition of a word or words in adjacent phrases or clauses, either to amplify the thought or to express emotion.)