have on ( see also ↑ have )
1 . have (got) something on to be wearing a piece of clothing or type of clothing:
He had his best suit on.
Jimmy had nothing on but his socks.
2 . have (got) the TV/radio/washing machine etc on if you have your television, radio etc on, you have switched it on and it is working:
Billie has the radio on all day long.
3 . be having somebody on especially British English to be trying to make someone believe something that is not true, especially as a joke:
Don’t believe a word he says. He’s having you on!
4 . have (got) something on British English to have arranged to do something, go somewhere etc, especially when this means you cannot do something else:
Sorry, I can’t help you this weekend – I’ve got too much on already.
5 . have (got) something on somebody to know about something bad that someone has done:
What do the police have on him?
6 . have (got) nothing on somebody/something informal to not be nearly as good as someone or something else:
Rock ‘n’ roll has got nothing on these African rhythms.