хандидан

хандидан: to laugh

Рустам аз шодӣ баланд хандид.
Rustam laughed loudly with joy.
Чаро механдед?
Why are you laughing?

Bonus:
Synonym: ханда кардан

хандаовар: funny (ханда: laughter + stem of овардан:to bring)
хандондан: to make somebody laugh
хандонрӯй: happy-faced, cheerful

Learn more verbs at Memrise: Tajik First 100 Verbs