Artist Disillusionment: Jeph generally likes his fans, but he hates his discussion forum due to its tendencies towards Serious Business and Shipping. At one point it got so bad that he openly threatened to delete the whole forum should people keep posting that kind of stuff. He has considerably softened up since then, realizing that the phrase "You can't please all of the people all of the time." is quite accurate.
Can't Take Criticism: Jeph literally got drunk and stabbed his hand over it, though to be fair, he had a lot of other stresses in his life that lead up to this event, and the criticism was just the final straw.
To a lesser degree, Jeph seems to detest when fans analyze or speculate over the direction the comic's narrative is taking.
Creator Breakdown: It turns out that if you combine quitting smoking with an apocalyptic hurricane and some truly spectacular Tumblr bullshit Jeph will snap. Or stab.
Creator's Favorite: Jeph rotates through a lot of them. Dora, Hanners, Marigold, Emily and Claire have been the main ones so far.
The Merch: Characters will sport a new funny slogan or t-shirt in a few strips, then Jeph will talk about it in his Info post, then it will show up in the Merchandise section. Doing a massive Archive Crawl, you could see this six or seven times in a short span. It ain't called the "Questionable T-Shirt Factory" for nothing.
Mutually Fictional: A really subtle one with Questionable Content and xkcd. Marigold wears an xkcd shirt here (and fangirls over someone who looks like Randall Munroe here), and this xkcd comic shows one of Hannelore's Twitter posts.
Shrug of God: When asked at a convention if Jeph will ever reveal if Penelope is actually Pizza Girl or not, his response was "I will... when I decide if she is Pizza Girl or not."
Teasing Creator: After being asked one too many times about where Steve has been, Jeph gives us this.
Trolling Creator: Long story short, Jeph Jacques has fun with shippers - so much, it was a tradition in the past to have "surprise kisses on friday", because there wouldn't be update between fridays and mondays. When asked about one Story Arc designed to piss off shippers in particular, his response was "See my entire comic". Ship Sinking is a common occurrence in the comic, but in Jacques' defense, breakups for real-life twenty-somethings can be just as sudden, so this trait makes the comic actually kind of realistic. That said, as mentioned elsewhere in other subpages, Ship Tease can truly reach epically ridiculous proportions, the epitome of which would be the early 2013 Story Arc where Marten, right after Claire revealed herself to be transgender, started to share a lot of screentime with her all of a sudden, going as far as asking her to accompany him to his father's wedding. The commentary for this strip outright says "I am trolling you guys pretty hard".
Although the trolling seems to have finally stopped with strip 2408, according to the commentary. Still, it's been four strips in a row being nothing but fan-trolling (at the expense of storytelling).