Actually "—˜¥" has a meaning of wish you lucky.
It is similar to '¨"N‹Ê in Japan.
"—˜¥" can also called g •ï or g •• •ï , ( in Cantonese, we used to call it —˜¥ rather than g •ï or g •• •ï, I think g •ï or g •• •ï are used more often in in Mandarin.)
—˜¥ is a little red paper made pocket filled with money. It acts as a present in many Chinese tranditional festival. Giving each other —˜¥ is a custom in China. The most common practise is to give —˜¥ to each other in Chinese New Year, wedding and birthday. Red colour represent happy and lucky in Chinese, so —˜¥ is in red colour.
Usually, only married ones give —˜¥ to others. Unmarried one no need. (but all people can receive —˜¥). However, these custom has changed a little bit. In some offices, unmarried one also need to give —˜¥ to others, I think this custom is diferent in different offices.