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1.
Blowing into your partner's arsehole while reaching round and wanking him off. With your lips pursed around his ringpiece and hand movement you will resemble someone playing a trombone
Give me a Dirty Trombone, baby, and I'll buy you 20 cigarettes
by Cwilliam September 27, 2006
 
2.
haha when danny tells you that a kid in his class tells you that if you blow in some dudes ass hole and jack them off from the back it looks like a dirty trombone hense...dirty trombone
wow alex workman "played" the best dirty trombone on me last nite ...phew
by mikey shabsove March 12, 2004
 
3.
When you pucker up and play a tune on a man's asshole while you trombone his cock.

Hand gestures really help to explain this one.
Eric didn't know how dirty Yvonne was until she gave him a Dirty Trombone...then he knew she was the gal for him.

or

Jeremy gave Todd a Dirty Trombone, and then they went rollerblading.
by Monkey Boy K July 05, 2006
 
4.
You have a female/ life partner sit on your lap. that partner then shats on your penis then proceeds to spread it around the entire shaft. You then take hold of your meat-stick and stick it into any hole off your choosing on the body of your partner.
Your vagina smells like you had a dirty trombone
by GettinDatPussy April 29, 2011
 
5.
While you are with two girls at the same time, you do one chick in the ass while the other licks your dick as it goes in and out like a trombone
Hey I did the dirty trombone with your two sisters last night.
by Dirk March 24, 2005