Hot dogs are called "glizzies" because the term "glizzy" originally referred to a Glock handgun. The slang "glizzy" emerged from Washington D.C. street culture, where it was a term for a Glock or its extended magazine, which shares a similar length to a hot dog. Over time, especially by the late 2010s and early 2020s, the term transitioned from meaning a gun to meaning a hot dog, popularized in part by D.C. rapper $hy Glizzy and viral social media trends. This transformation was also aided by references in hip-hop culture and the online "glizzy" meme phenomenon.

In summary:

• "Glizzy" was originally hip-hop slang for a Glock handgun.
• The similarity in length between a hot dog and a Glock's extended magazine may have inspired the new slang.
• It became popularized in Washington, D.C., especially by rapper $hy Glizzy.
• The term went viral as a synonym for hot dog on social media platforms in the early 2020s.