When does Ukitake give Toshiro gifts?
It's a Japaneese joke. Ukitake's full name is Joshiro Ukitake and Toshiro's full name it Toshiro Hitsuguya. Joshiro and Toshiro sound similar and the names have similar charectors. Also, they both have white hair. Ukitake finds this is perfect reason to give Toshiro gifts, for some reason. It's funny because he always ends up giving it to Yachiru, the vice-captain of squad 11.