an 'underhand' [=('US') 'underhanded', ('Brit') 'underarm'] throw
Throw the ball 'underhand'.
an 'underhand' deal/tactic
(..) You think he could have made the wound that killed his father? No. Not with the experience he got all his life handling these things. - I feel he'd have gone for him underhand. - How do you know? - Were you there when he was killed? - No. Neither was anybody else. What are you giving us this (..)1957 12 Angry Men
(..) I guess you try to forget. - How do you use a switchblade? - Well, you'd never use it like this. See, you'd lose too much time switching hands. Here's how. Underhand. Anyone who's ever used one wouldn't handle it any other way. - Are you sure? - I'm sure. - It's why they're made to open like that. (..)1957 12 Angry Men