Adverb
(simile) Very straight; travelling in a very straight trajectory.
Synonym: arrow-straight
(simile, by extension) Having no homosexual desires or thoughts; completely heterosexual.
Source: en.wiktionary.orgI'm actually a pretty decent human being, and when I'm home I'm straight as an arrow. Kid Rock
It made me strong.I took a step back, near my whole self in the mirror.I pushed back my shoulders and raised my chin, my back straight as an arrow. Laurie Halse Anderson
I disagree, but I think he’s straight as an arrow when he talks how radical the left is and how dangerous their policies are. Source: Internet
“She is straight as an arrow. Source: Internet