Whenever I see a Spanish-speaking person convey laughter through an instant message or other text, I go through a three-step process:
1. "Huh? Jejeje?"
2. "Oh yeah. Other languages are funny." (smile)
3. Then, I continue smiling, because I think of that Simpsons episode where the students are laughing at Lisa, and the French teacher instructs them to laugh at her "en français" instead.