Twin glizzies, alternatively spelt "Twin glizzy's" refers to dual-wielding two Glock pistols of any model in both hands, though is more specifically referring to dual-wielding the fully automatic Glock-18 model of pistol. The term is most often associated with gangsters and rappers, and is commonly referenced in many rap songs. Note that although Glizzies refers to Glocks, it is sometimes also applied to reference any pistol of any variety.
A derogatory way to describe someone who is very busy with sexual endeavors. Most often used to describe someone engaging in gay sexual activity involving more than one boom tube.
Knowing Roy, he was probably three glizzies busy last night.