On Father's Day

भौतिक विज्ञान (Physics) के अध्यापक ने समझाया, 

मात्रा वज़न और वेग (Momentum) बदल सकती है 

दिशा नहीं। 

माँ सहेली से बोलीं, 

"इनका तो तुम जानती ही हो। अब रोज रोज क्या कहना!" 

मैं बोला, 

"मेरे पापा के तो क्या कहने!" 

* This is a wordplay on 2 figures of speech and 2 meanings of the same word in Hindi

क्या कहना (resignation) and क्या कहने (praise)

मात्रा means quantity and the addition of the vowel to the consonant in the Hindi script. 

In the first paragraph, 

The Physics teacher explains that quantity (Matra) can change 

the mass 

and the momentum of a body

but not its direction. 

In the second paragraph, a change of matra (vowel) changes the direction of the insinuation completely. In the first line, the mother uses a Hindi phrase (Kya Kehna) that usually indicates resignation (in this case, to her husband's habits). 

In the second line, the child changes one vowel sound (Kya kehne) and this phrase means "My dad is incomparable! in a complimentary way.