Correction: checking the code, the game is working properly, and I found how to unlock Mrs. L's blowjob the legit way.
You need to go into detention four times. The fourth time it happens, you get the BJ scene.
Detention was retroactively added to the following older scenes:
1. Stolen Hearts - steal the doughnuts while Jacklyn is in the cafeteria. Then say "it's not what it looks like". Jacklyn will give you a detention point.
2. The Glowing Spider Eggs - requires Jacklyn to have less than 4 hearts towards you. When sneaking into the women's bathroom, choose to masquerade as a statue without silver paint. The guard will catch you, and you'll get a detention point.
3. Spell You Later (1) - requires four or more lust. When the soda fountain is on fire, pee on it. Jo will catch you and give you a detention point.
4. Spell You Later (2) - "hide" in the science lab by masquerading as a statue, just like in the spider eggs quest. It does not work, again. But you'll get another detention point!
And with the new scene:
5. In for a Dime, In for a Dollar - just complete the quest, arsehole guard will go after you.
