Male, female or mixed sex couples/groups who meet to masturbate socially.
A non-marital partner who lets you watch them 'play'.
Jeff and Steve were regular wank-mates in 6-8th grade.
Debbie and Sally enjoyed frigging together before going clubbing.
Fiona and I enjoyed a regular wanks in her parents garden-lodge, last summer. She's a good wank-mate always ready to get her knickers down and rub.