A random hookup is more towards a "casual encounter" rather than a "sexual encounter". It is not synonymous with a "casual encounter" but it leans in that direction, being a stronger term ("random" is an extreme of "casual" and "hookup" is a rude version of "encounter").

Sexual Encounter - definition of Sexual Encounter by Medical dictionary - a completely neutral and generic term

Have you made any progress - the summer is over, the new academic year is here... have you found ways to dress both comfortably for you and without being off-putting in the eyes of others?