Is precum in guys like vaginal wetness in girls? Is it a similar process? (-question asked during a sex ed talk.)
No. Vaginal wetness comes internally from transudation (water content in plasma pushes past cell walls when blood vessels/capillaries become engorged) and externally from the Bartholin’s (greater vestibular) glands. Lubrication is part of the arousal process in females and can vary greatly due to a long list of factors.
Precum, on the other hand, occurs for a very different reason: to prep the urethra for safe sperm transportation. Urine and semen both pass through the urethra in males. Because urine is acidic enough to kill sperm, males secrete a small amount of fluid prior to ejaculation to create a more alkaline environment.
Be aware: precum still contains enough sperm to impregnante someone.