This poem was actually from Alice to Fliqpy, a poem seen in a gallery of love letters, and valentine requests in the episode Valentine's Day!.
"Roses are red, violets are blue, "
"Be my valentine, I'm waiting for you,"
"Blood is red, bruises are blue,"
"Anyone besides Flippy reading this,"
"I'll kill you."
When the poem gets violent, it is written in neat, but bloody writing.