眼镜一摘，火力全开

Meaning

"双喜" (double happiness - two people's joy) combined becomes "囍" (double happiness character), meaning two people like each other and get together. In Chinese weddings, the "囍" character is displayed. The second part "怕我只是喜" (afraid I'm just one '喜')" expresses the fear of unrequited love - only I like them, they don't like me, so we can't be together.