A leisurely form of sexual penetration in which the male is lying on his side behind the female, and inserts from up and under. Best enjoyed in the morning hours, when the girl is not yet awake enough to object to this impersonal form of coitus, one that becomes very personal by its grand finale.
n. the sideslip, I gave her the sideslip
v. to sideslip, sideslippin on 4, 4s, she got sideslipped last night
Ronald: "Hey Billy, what'd you do with Sally after the bar?"
Billy: "Well Ronald, we went back to my place and I eskimo'd her down the stairs. But then this morning, once I put my pocket-t back on, I gave that bitch the sideslip. She met the business end of my d!$%"