Inclusion Criteria:

1. aged ≥16 years;
2. full-time undergraduate college students;
3. engaged in risky sexual behaviors (including multiple sexual partners, unprotected sex, and casual sex, and one of them is considered to have engaged in risky sexual behaviors) during their college years;
4. able to clearly recall and describe the incident;
5. signed an informed consent form

Exclusion Criteria:

1. not wanting to be asked sex-related questions;
2. being screened at the beginning of the semester using the Mental Health Survey and diagnosed by a psychiatrist as having a mental illness (schizophrenia, major depressive disorder, bipolar disorder)