toy boy 
noun British informal
A male lover who is much younger than his partner.But now here was something they couldn't share - a toy boy who threatened to drive a rift between their sisterly love… forever!...
- Instead of a toy boy, she invests in a run down theatre off Shaftsbury Avenue in London's West End and renames it The Windmill, after the street in which it resides.
- We were accompanied by a younger man who could have been a toy boy but seemed more like a paid amanuensis whose role was to heave the portly baronet into a taxi when his behaviour put him in danger of arrest.