Acronyms. IIRC is "if I remember correctly" or "if I recall."
MBTI is the Myers-Briggs Type Inventory/Indicator, a personality test that uses eight traits (Introversion, Extraversion, Sensing, iNtuition, Thinking, Feeling, Judging, and Perceiving).
LOL is laughing out loud, and SMP is Science, Math, and Philosophy (LDO).