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1.
On the phone; talking on the phone
A: She gave me her phone number two days ago
B: You had better get on the horn pretty quick if you want her to go out with you
by theone1103 August 06, 2012
4 1
 
2.
A command issued toward a potential administrator/administratrix of fellatio.
On the horn, bitch!
by Jeff O. January 18, 2003
8 8
 
3.
when the male penis is erected, sometimes "on the horn" is used to explain an inappropriate erection
1. I was on the horn, but she didn't even notice. (sad face)

2. Oh lordy, is he on the horn?
by ClaraFloraKavy March 20, 2011
1 2