Green’s Dictionary of Slang

an erection; usu. in phr. to slip her the woodrow, to have sexual intercourse with a woman.

1989		J. Doyle College Sl. Dict. 🌐 slip ’er the Woodrow, to [USC] to sleep with.
2002		T. Dorsey Triggerfish Twist (2002) 171: A few guys get woodrows watching women’s feet.