Thanks for reaching out to EmpowHER!
When semen is outside of the body, it does dry up and can not get you pregnant. Actual sexual intercourse and penetration must occur in order to get pregnant.
As time passes and semen is in open air, it does dry and would not be able to get someone pregnant. Tell your friend to check out this article: https://www.empowher.com/community/share/outercourse-dry-humping-dry-sex...
It does a great job at explaining what can and can't get you pregnant.
Hope this helps!