It's not impossible. I mean, they did say they'd add traps like the plant trap. There's three version that's possible, which I'll list from hardest to easiest to impliment:
1) Turns Joe into a playable Daku. A trap, an enemy attack (like a magic bolt), turning him into a weaker creature. Plus, it could double lust increase given he's tiny and likely used as a fleshlight by bigger guys. It's the hardest as you need new sprites, coding the transformation, the new grapples, the new attacks, everything.
2) It's a grapple animation. A ranged grapple. Again, like a magic bolt, it hits Joe and he poofs into a Daku. The attacker then poofs next to him and sex ensues. Second hardest as now you need to code a ranged grapple and a teleporting enemy.
3) A trap. Trap goes buuurrr, Joe goes poof, then sex happens (I'd suggest like a Daku ninja squad: Joe goes poof, they smokebomb in, group sex occurs, but that's just me).
There. Not impossible, just different ranges of difficult. ^^