Gustakhi – means being audacious or wayward and cheeky in a fun way; obstinate or stubborn in some cases.
Here is a beautiful song from the movie Hum Dil De Chuke Sanam, that paints a beautiful picture by using this lafz in the context of the play of eyes.
Aankhon Ki Gustakhiyaan Maaf Ho
Ek Tuk Tumhein Dekhti Hain
Jo Baat Kehna Chaahe Zubaan Tumse Vo Ye Kehti Hain
Aankhon Ki Sharmohaya Maaf Ho
Tumhein Dekhke Jhukti Hain
Uthi Aankhein Jo Baat Na Keh Sakin
Jhuki Aankhein Vo Kehti Hain
Aankhon Ki Gustakhiyaan Maaf Ho
Kaajal Ka Ek Til Tumhare Labhon Pe Laga Loon
Haan Chanda Aur Suraj Ki Nazron Se Tumko Bacha Loon
Oh Palkhon Ki Chilman Mein Aao Main Tumko Chhupa Loon
Khayaalon Ki Ye Shokhiyaan Maaf Ho
Har Dam Tumhein Sochti Hain
Jab Hosh Mein Hota Hai Jahan, Madhosh Ye Karti Hain
Aankhon Ki Sharmohaya Maaf Ho
Ye Zindagi Aapki Hi Amaanat Rahegi
Dil Mein Sada Aapki Hi Mohabbat Rahegi
In Saanson Ko Aapki Hi Zaroorat Rahegi
Is Dil Ki Naadaniyaan Maaf Ho
Ye Mere Kahan Sunti Hain
Ye Pal Pal Jo Hote Hain Be pal Sanam To sapne Naye Bunti Hain
Aankhon Ki Gustakhiyaan Maaf Ho
Sharmohaya Maaf Ho
English translation –
May the impertinence of my eyes be forgiven…
They look at you just a little; and what I have longed to say you, they express it to you.
May the bashfulness of my eyes be forgiven.
My eyes fall away from yours; what my eyes couldn’t say while looking into yours, that lowered gaze says instead..
May the impertinence of my eyes be forgiven…
I will place a dot of kohl on your lips
Come, let me hide you behind the margins of my eyelashes, May these mischievous thoughts be forgiven.
With every breath (my eyes) think of you, and though the whole world is in its senses,
I lose my senses..
May the bashfulness of my eyes be forgiven.
This life (of mine) will always be yours.
For you, love will always reside in my heart.
Even just to breathe, I will always need you.
May these follies of my heart be forgiven.
When have they ever listened to my words;
These eyes, always restless with desire, they weave new dreams every moment.. May the impertinence of my eyes be forgiven….the bashfulness of my eyes be forgiven.
Here is the link to the song:
urduwallahs 
hmmm i like the shiri