Don't

According to my textbook, you tell someone not to do something by adding -me to the end of an informal command. Example follow.

• Gelmek: To come; Gelme!: Don't come!
• Yapmak: To do; Yapma!: Don't do!
• Koymak: To put; Koyma!: Don't put!
• Gülmek: To smile/laugh; Gülme!: Don't smile/Don't laugh!

Formal versions of the above follow:

• Gelmeyin!
• Yapmayınız!
• Koymayın!
• Gülmeyiniz!

Reminder: -y- inserted to avoid vowel clashes.

Personal note: I like the word gülmek. Its full definition at www.turkishdictionary.net follows:

1. to laugh.
2. to be happy, experience happiness.
3. to have a good time, have fun.
4. /a/ to laugh at, make fun of.
5. /a/ to smile on. Gülerim!/Güleyim bari! Oh really?/How interesting! (sarcastic way of showing disbelief).

It's the root word for saying goodbye: Güle güle (said by the one who is staying to the one who is leaving).

Other pleasant variations follow:

Good luck! Güle güle gidin(iz).
Have a good trip! Güle güle giyin(iz).

There are more. However, www.turkishdictionary.net is offline as I type this entry. Hopefully, it'll be available by the time you read this.