All the sex jokes
Okay, I get that the movies are PG-13. I get that you're allowed to fill them with whatever you want. But this is a TRANSFORMERS movie! Kids across America are gonna see it. So why would you fill it with innuendos?
On top of that, some of these innuendos made no sense in context. Take Wheelie humping Mikaela's leg for example. Where did that come from? What was the purpose for it? And some of them get downright uncomfortable. Like the infamous "Sam's Happy Time" scene.
And before you say "They're allowed to be whatever they want for new audience members", ask yourself: How in this day and age can anyone grow up without knowing about Transformers? Everyone has expectations for these movies, and they're mostly appealing to teens.