"b4 I 4get..."

• Afterthought introduction, when texting
• "Incidentally," in online shorthand
• "One more thing..." online
• "Oh, I almost forgot," in a text
• "Before I forget..." for short
• "I meant to tell u ..."
• "Just so you know...," in a text
• Texter's "Oh, and another thing ... "

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
Internet abbreviation of by the way , in use by 1989.