Sham El-Nessim is a feast celebrated by Egyptians. The word “Sham El-Nessim” is an Arabic word borrowed from Coptic “Ϭⲱⲙ ̀ⲛⲛⲓⲥⲓⲙ“. This feast always follows the Eastern Christian Easter (according to the custom of the largest Christian denomination in Egypt, The Coptic Orthodox Church). It refers to the beginning of the spring.
Originally, this feast was celebrated by Christians only, but nowaday, it is celebrated by both Christians and Muslims. We spend this day in the green gardens and smell the fresh air (mixed by the salted fish smelling 🙂 )
If you want to know more about this occasion, visit this link on Wikipedia takes about Sham El-Nessim