(Just a test run)

Optimus:

His face started to turn a dark red as he finished his workout at the gym only to realize he had popped a boner while thinking about his lover waiting for him at home.. smooth Optimus.

Bumblebee:

He stood there with a red face as he got out of the pool in school, his whole class saw it, even his new girlfriend who was the one to throw a towel at him to wrap up in as he ran to the locker rooms. It was quite an impressive display. Of him running off and almost slipping that is.

Smokescreen:

He stood there in his tight new jeans Miko picked out, said it would make him look 'hip', not only could you see his hips but what was directly in between them. He wasn't sure why or how it happened and didn't even realize it until he took notice of kids laughing as him and Miko walked down the hall "ahem.. smoke.." Miko blushed as she glanced away while pointing down. "Oh, primus.." he muttered as his face turned red, he rushed to the bathroom.

Bulkhead:

He popped a boner, right in front of Miko, too. If that wasn't bad enough of doing in front of his charge it was pretty bad to say there was a full beach of people filled with men, women and young children and it made it worse when a kid pointed it out as Bulkhead shamefully wrapped up in a towel and went back to their hotel with Miko and Wheeljack.

Ratchet:

He coughed uncomfortably when he felt his crotch tense up after performing a prep job on a younger femme at work, his face turned red as he excused himself quickly while yanking his jacket in front of the unfortunate erection. Hey, at least she didn't see otherwise she might have reconsidered her doctors.

Wheeljack:

He popped a boner in the gym showers, public mind you as a man walked by and grabbed his shoulder "Good thing you're already in the shower" he said before walking on "huh?" Wheeljack looked down and gave a uncertain groan "aw, slag.." another guy came up behind him, clearly gay. "Looks like someones a little too excited.." "Frag off.." Wheeljack grumbled and he quickly scrubbed and wrapped up before throwing on clothes, he was still cold and wet but he definetly didn't have the boner as he seen Bulkhead waiting outside "where were you? It's been 30 minutes." "I don't want to talk about it.." he muttered as he walked away with Bulkhead to quickly follow without question.