I am standing right here, so do not treat me like chopped liver.
chopped liver
idiomA person or object not worthy of being noticed; someone or something insignificant.
Origin
disputed originCalque of Yiddish געהאַקטע לעבער (gehakte leber), from געהאַקטע (gehakte, “chopped”) (compare the verb האַקן (hakn, “to chop”)) + לעבער (leber, “liver”). According to the Hungarian-American lexicographer and linguist Sol Steinmetz (1930–2010), sense 2 (“person or object not worthy of being noticed”) may be from the fact that chopped liver is served as an appetizer or side dish rather than as a main dish.
I spent all day helping you with this project, but you act like I am chopped liver.
Despite his significant contributions to the research, he felt like chopped liver when the board ignored his suggestions during the final meeting.