Disclaimer: Naruto isn't mine.
Jiraiya had a lot in common with the bullfrog; he was large, hungry, horny and generally ought to be avoided, if possible.
This did not mean that he was completely horrible. After all, even the loudest fool has some admirable traits. He had, for example, a rather large bank account, coupled with excellent taste in sake. In other words, he was the ideal drinking friend.
And if you were in the mood to get truly shit-faced, he knew all the right places to go. Places where they didn't kick you out when you couldn't stand up by yourself anymore.
The women in places like those didn't care if you couldn't find your mouth with your glass, or if you couldn't put out in bed. They didn't even care if you couldn't find your wallet when the bill was presented, as long as could find somebody's - and Jiraiya's thick wallet felt awfully good in Shikamaru's back pocket at the moment.