How many letters does the top answer for “what happens when you roll 3 doubles in a row in monopoly” have?

The most common answer is go (2 letters).

Crossword clue: what happens when you roll 3 doubles in a row in monopoly

3 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

go 2 letters otdb

change location; move, travel, or proceed, also metaphorically

jail 4 letters otdb

a correctional institution used to detain persons who are in the lawful custody of the government (either accused person

to 2 letters otdb

An obsolete intensive prefix used in the formation of compound verbs; as in to-beat, to-break, to-hew, to-rend, to-tear.