oh, btw 情人节 (qíngrén jié) is chinese internet valentine's day/ a romantic day. most people know it as 5.20 or the 20th of May, because it sounds close to the phrase 'i love you' or 我爱你 (wǒ ài nǐ) while 520 (wǔ'èrlíng)when said in a fast way sounds a lot like 我爱你.
but be aware that this is only in Mandarin! in Cantonese 520 is 唔愛妳 (wú àǐ nǎi) which translates to 'don't love you'.