Here are two videos that look promising:
Here's the writeup from the site:
Superman- The Weakness
Supergirl gets together with her cousin - Superman - wanting to discuss some recent discoveries that she's made.* Her plan is to gain notoriety as THE strongest of the two and in order to do this - she must show that Superman has a weakness.* She learns that Superman can be weakened and overpowered by females who arouse and manually stimulate him.* This has the same effect on Superman as kryptonite.* As they struggle - with Superman easily overpowering her, Supergirl reaches down and starts to stroke the superhero's cock.* Watching her cousin weaken, Supergirl continues in her feisty manner to totally weaken Superman to show who is the strongest.* Supergirl teases him - taunting him verbally about how weak he is - showing his weakness by asking him to lift something (he struggles mightily) -- stroking him weaker and weaker until he falls unconscious.
And here's the summary:
Superman- The Weakness Vol #2
Lex Luthor has discovered that Supergirl has seduced and weakened her cousin - Superman - leaving him helpless.* He decides to use this knowledge to overpower and capture Superman -- with a little help with his pretty young niece Luticia.* He asks Luticia to set a trap for Superman - pretending that she's being attacked so the superhero will come to her rescue.* Showing Superman how she was attacked - she quickly gains the advantage by grabbing him from behind and quickly massaging his penis.* He tries to stop her but is soon too weak to resist.* Luticia continues this stroke and stop method to keep the superhero down and defenseless.* She calls her uncle Lex Luthor to let him know that his plan has worked and that she'll keep this up - not allowing Superman to cum until Lex Luthor begins the second part of his plan.