We see and interpret signs every day, and these signs mean something different to each individual person. Most signs can be interpreted mutually and generally draw the same conclusions, but sometimes this isn't the case and that is why I don't think that signs are stable or objective in their meanings. Semiotics can be defined as the "study of social production of meaning from sign systems; the analysis of anything that can stand for something else" (Griffin, Ledbetter & Sparks, 2015, p. 327). Anything that can stand for something else means that there can be multiple meanings, which wouldn't make a sign the same to every person and therefore not stable.
For example, a sign in one culture can have a different meaning in another culture. Even within the same culture, signs have different meanings to different people. Take Beyonce's performance at the Superbowl--Beyonce performed her new song, "Formation," during the Superbowl half-time show. Controversy surrounded the performance as well as the music video released the day before after the fact about the different interpretations of these performances. Many believed that her performance was in support of the "Black Lives Matter" movement as well as her costume representative of the Black Panthers. In an article by Brasted on Beyonce's music video released the day before the Superbowl, different media networks interpreted what her performance and music video meant to them. A columnist writer for NPR wrote that Beyonce's performance was "glorifying her bama blackness" while Wortham from The New York Times stated "It's also not insignificant that she's electing to
parade her substantial wealth and ability to outearn most men in the music
industry (including her husband, Jay Z) during the Super Bowl — the flagship
event of male virility and violence in this country. That's incredibly
meaningful. It's a moment where the entire country will be watching, and forced
to sit up and pay attention" (Brasted, The Times-Picayune). Others believe Beyonce's song is a protest
against the police which has caused some protests and boycotts mentioned in the article; everyone has an opinion and a different
interpretation. But the point being that
Beyonce's song means something different to to everyone that interprets the
message she was trying to convey.

References
Brasted, C. (n.d.). Beyonce Super Bowl halftime show leads
to protests, boycotts, conversations. Retrieved March 12, 2016, from
http://www.nola.com/music/index.ssf/2016/02/beyonce_boycott_racist_protest.html
Griffin, E. A., Ledbetter, A., & Sparks, G. (2015). A first look at communication theory(9th
ed.). New York: McGraw-Hill.
picture from: https://www.google.com/search?q=beyonce+formation&espv=2&biw=1366&bih=667&site=webhp&source=lnms&tbm=isch&sa=X&sqi=2&ved=0ahUKEwjou-PumbzLAhUMWh4KHTV7D4EQ_AUIBigB#imgrc=Qgi0cM5l-LvBpM%3A